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In another thread it was mentioned doing fake case coloring by using a torch and urine. I've never heard of this. Any info would be appreciated.
I've also heard that the case colors on modern replica firearms, such as Uberti, are not actually from true case hardening. My Uberti 1873 Winchester has beautiful case colors, wonder how it's done?
Thanks, John...
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John,
Forget about using a torch at all,I don't know about urine; I believe horse urine may have been used for browning barrels in the old days.Again, forget about using a torch.
Mike
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I've also heard that the case colors on modern replica firearms, such as Uberti, are not actually from true case hardening. My Uberti 1873 Winchester has beautiful case colors, wonder how it's done?
Thanks, John...
John, There are two types of case color hardening commonly used for firearms, neither are thru-hardening of the steel but topical skin case hardening........A.) Bone and charcoal case color hardening........B.) Cyanide case color hardening........ Uberti uses cyanide case color hardening as does Pedersoli, Beretta, Armi-Sport and some other Italian makers..... Bone and Charcoal case hardening is run at a higher furnace temperature than Cyanide case hardening......as well as the obvious different sources of rich carbon......both have benefits for various applications..... People with a torch are in the "shade tree" category, if that, with or without urine LOL, as are the faux (fake) topical kit painters, fake patina applicators and the like etc...... and they look exactly like what they are, junk....... Multiple posts have been made here over the years, covering every possible detail of these various processes.....you can look them up should you be interested in specifics......
Doug
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Arrieta uses a cyanide process as well.
Such a long, long time to be gone, and a short time to be there.
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Thanks for the info, just curious. I kept thinking about someone putting a torch to a gun after pouring urine on it. Sounded like something a liberal would do.
John...
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Obviously you have confused ed good with somebody who knows what he's doing.
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Case Hardening was developed many yars ago to put a hard surface (Case) on low carbon steel or iron which would not harden by the heat & quench method of higher carbon steel. Without going into a lot of detail when the steel was heated above its critical temperature & held for a period of time in a carbon atmosphere the carbon was absorbed into the surface of the steel. A quench then would harden the higher carbon surface (Case) but not the inner core which was still of a low carbon content. The technical term for this is Carburizing & hardening. It generally became known as case hardening & when done with color Color Case Hardening. The nice colors were actually a by product of the process normally occurring when Animal charcoal was used for the carbon source. Alloy steels containing more than about 20 points (.02%) carbon are not normally carburized but heat treated which does not produce color. Several makers of modern guns have developed methods of producing some color on their gun parts which are not true "Color Case Hardening" but simply a chemical color process.
Back at the point in time Ithaca was importing the Perazzis, these guns receivers were made of an alloy steel which was heat-treated & subsequently "Colored". Ithaca published in a gunsmith manual they put out their recommended procedure for "Re-Coloring" one of these. It consisted of; Heating the part "Evenly" with a "Torch" to about 200°F or until it would just start to sizzle a dab of water. A Q-Tip wasa then dipped in cold bluing solution & dabbed, sprinkled or streaked on. They then recommended a coat of clear acrylic to protect the colors. Ithaca recommended 44-40 blue, I have tried Brownell's Oxpho & could tell no difference.
Several things of note;
1st - an most important, this method should never be confused with the process of holding the tip of a torch in one spot on a part which has previously been hardened by any method, either case or through, until the part takes on a "Temper Color".
2nd - This method in no way heats the part any hotter than a boiling water bath of a rust blue & definitely not as hot as a Sale Blue bath. this process in no way damages any previously imparted heat treatment it may have received. The colors produced are very thin & if un-pleasing can simply be poilshed off.
3rd - This will "Never" produce the colors of a true Bone Charcaol Color Case Hardening. But at a cost of about $5.00 as opposed to the price of a Bone hardening job it has its place.
I personally would not care to spend $300.00-$500.00 on a gun which would be Worth about $250.00 when it was finished. Whether or not is is preferable to simply leaving it worn, rusty or shiny is purely up to the individual owner. Actually with a bit of practise one can produce a finiash which to me is about as attractive as the average Cyanide finish.
Miller/TN
I Didn't Say Everything I Said, Yogi Berra
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2-piper, thanks for the info. I've always wondered about the method the old timers used to produce the colors. It seems the method is almost a science. It's just an procedure I an interested in. Your post explains a lot !
Again, thanks for the info!
And who is ed good ? Just curious,,,
John...
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skratch, the colors are closely related to the actual thickness of thin films of oxides and other surface compounds that will cling to the steel surface. Browning and blueing use iron oxide, red is ferrus oxide Fe2O3, and blue/black is ferric oxide Fe02 - red and black rust.
Steel can be hardened without coloring and coloring can be done without hardening. However, the bone charcoal process both hardens the surface and colors it. Case colors are very thin and do not change the hardening if worn away.
ed good was involved in some gun restorations that are/were questionable in the eyes of many on this board particurally due to torch recoloring.
DDA
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Very early on, gunsmiths would immerse a wrought iron spring in molten lead, then quickly quench it in linseed oil. The spring was then placed over heat to temper it. The gunsmith gauged the amount of tempering by the color, yellow, then violet, then blue. Pale blue was used in tempering springs.
This can be seen in the video, "Gunsmith of Colonial Williamsburg" with Wallace Gusler.
Pete
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Others have detailed the process of bone charcoal case hardening which imparts colors to the surface as well. Over the years, gunsmithing books have told of the various mixes of charcoal, charred leather, and such that were added to the crucible. Some say that some gunsmiths urinated in their secret charcoal mix to get different colors. I suppose anything is possible, but it wouldn't be pleasant. Actually, it seems the quench process has more to do with getting vibrant colors than the pack, but it's probably both... and the steel... and the temperature... and the time... The folks who do it well are often pretty secretive about their process.
When I was an apprentice electrician, I spent several months working in a blast furnace. The restrooms were some distance away from the cast house, and as a prank, occasionally someone would urinate in an iron runner between heats. When the furnace was tapped and the molten iron hit the urine soaked coke dust lining the runner, it would flash to steam, often with an impressive explosion. The smell would fill the cast house, and it was nasty. Very nasty! Even though the cast house had no sheeting on the sides, and the cold winter winds were blowing through, the aroma was disgusting. Superheated human piss smells far worse than any skunk. I can't imagine that anyone would intentionally heat urine with a torch to put fake case colors on a gun. But people do some strange stuff. It sure wouldn't make your wife or neighbors happy. Maybe Ed will chime in.
A true sign of mental illness is any gun owner who would vote for an Anti-Gunner like Joe Biden.
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he a we go a gain...
Heating any shotgun receiver without controlling the temperature and heat duration is potentially dangerous and can damage guns and potentially harm shooters. If a shotgun receiver is heated to critical temperature, such as that required for the bone charcoal surface hardening process to be effective, then the structure of the surface metal has been changed and the metal should be tempered back to provide some elasticity. Otherwise, the receiver is as brittle as glass and may crack upon firing of the gun.
Incorrect tempering of receiver surface metal is the inherent flaw in the use of the high heat bone charcoal process when applied to shotgun receivers. A dangerous situation may develop as a result of incorrect tempering of the receiver surface metal after the high heat bone charcoal coloring process is completed. This is particularly true of older shotgun receivers, made prior to ww2. Factory tempering specifications were inconsistent, as receiver metallurgy formulas changed from time to time. Unfortunately, much of the original factory hardening and tempering specifications have been lost. Even the best of mechanics are only guessing when they attempt to correctly re temper a shotgun receiver after subjecting it to a high heat bone charcoal hardening process.
Quality case coloring should provide cosmetic enhancement without endangering gun integrity or shooter safety....Be careful if you are contemplating sending your prized shotgun's receiver to a high heat bone charcoal mechanic.. He is going heat it up to around 1500 degrees F... Make sure that you get it in writing, that if the receiver warps in the heating and tempering process or that if it cracks after firing, then the mechanic will assume full financial responsibility for the destruction of your gun and/or your personal injury.
A low, controlled heat process, combined with specific chemicals is the safest way to recolor a shotgun receiver. So long as the heat is kept low and controlled, the original receiver metallurgy and heat treatment is not changed. No harm is done to the gun nor is there any potential for danger to the shooter, as a result of the re coloring process.
In summary, shotgun receivers should never be rehardened in the vain interest of restoring the cosmetic effect of case colors. Case hardening is a high heat process which alters the surface molecular structure of the receiver metal. Rehardening a receiver can warp it. Subsequent efforts to straighten the metal, either by bending or filing can only harm the fine original metal-to-metal fit and adversely alter the workings of carefully aligned internal shotgun parts. In addition, if the receiver surface metal is not correctly retempered after the hardening process, then the receiver metal may be too brittle and as a result, may crack upon firing.
Last edited by ed good; 05/25/13 08:25 AM.
keep it simple and keep it safe...
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Can anyone describe the cyanide-coloring process in detail to me? Apparently this process is used by some Continental gunmakers.
The only constant in life is change.
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Deleted
Last edited by AmarilloMike; 05/26/13 08:14 PM.
I am glad to be here.
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he a we go a gain...
Quality case coloring should provide cosmetic enhancement without endangering gun integrity or shooter safety....Be careful if you are contemplating sending your prized shotgun's receiver to a high heat bone charcoal mechanic.. He is going heat it up to around 1500 degrees F...
Ed, yep, here we go again.......as I remember we've had some 20/30 plus pages of discussion on this subject , more than once, with input from those, like myself, who actually do quite a bit of firearm color case hardening..... Your temperature windows are all wrong as usual, as is your doom and gloom scenario....... Only an idiot would fry parts at what you propose....... After re-casing a large volume of guns over the years , I haven't seen one yet that I did, end up with problems.... Can't speak for others, but the process is well defined and it's been around since man began building swords..... I helped Tony Treadwell with his CCH as he began, helped him with supplies and hands on problems, processes, do's and don'ts etc....... Tony as a novice and hobby gun smith using an electronic ceramic kiln/furnace had no problems and turned out some very nice CCH work consistently using time proven parameters and processes...... Color case hardening firearms has been with us at least 300 years or so and manufacturers still use basically the same processes and time lines, temperatures, quenches etc.... Gun Smiths who re-case color guns use the same numbers as well, as it is very well defined in the industry, with great success on a regular basis ...... I'm not going to debate all the details and try to convince you that frying a shotgun receiver with your torch is nasty and ugly, but it is, we've been over it before Ed, many times.....otherwise the factories that manufacture guns and "re-case" their own products, like Colt Firearms, would use YOUR TORCH METHOD.....LOL... This poor old field grade gun of mine that I re-cased years ago has had at least 5 to 8 thousand rounds fired through it over the years and is still giving as new performance..... I would be glad to put it up against any of your "torched" guns as a comparison for steel to steel fit, beauty, strength and longevity..... Best,    OR THIS ONE, OR ANY OF THEM ...........   
Doug
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Doug,
Do you do color hardening for other collectors than yourself. Your work is exceptional!
Larry
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well then, buy all means fire up the furnace and start cookin dem receivers... http://wn.com/what_is_case_hardening
Last edited by ed good; 05/25/13 12:15 PM.
keep it simple and keep it safe...
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re: cyanide case coloring...most guys who try it are usually dead before they finish their first job...
keep it simple and keep it safe...
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Awe, come on Ed, looks like Doug's examples came out pretty good. Thanks for showing us your method. It seems pretty basic, but those colors came out real nice.
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well then, buy all means fire up the furnace and start cookin dem receivers Here we go again...  Pete
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Just a further clarification: during the CCH process does the surface pick up additional carbon and that is what lends to the color and thin veneer of hardness? I always assumed (perhaps incorrectly) that the molecular structure did change slightly at the surface (to create the hardness) and that the color was a function of the material that was in the fire--the bone, leather and charcoal, pee whatever. I'd love to hear Miller's opinion and some others on this. thanks!
[IMG]
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Doug,
Do you do color hardening for other collectors than yourself. Your work is exceptional!
Larry
Thank you kindly for your compliment Larry, PM sent.... Best,
Doug
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uh...could you guys maybe, get a room?
keep it simple and keep it safe...
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he a we go a gain...
Heating any shotgun receiver without controlling the temperature and heat duration is potentially dangerous and can damage guns and potentially harm shooters. If a shotgun receiver is heated to critical temperature, such as that required for the bone charcoal surface hardening process to be effective, then the structure of the surface metal has been changed and the metal should be tempered back to provide some elasticity. Otherwise, the receiver is as brittle as glass and may crack upon firing of the gun.
Incorrect tempering of receiver surface metal is the inherent flaw in the use of the high heat bone charcoal process when applied to shotgun receivers. A dangerous situation may develop as a result of incorrect tempering of the receiver surface metal after the high heat bone charcoal coloring process is completed. This is particularly true of older shotgun receivers, made prior to ww2. Factory tempering specifications were inconsistent, as receiver metallurgy formulas changed from time to time. Unfortunately, much of the original factory hardening and tempering specifications have been lost. Even the best of mechanics are only guessing when they attempt to correctly re temper a shotgun receiver after subjecting it to a high heat bone charcoal hardening process.
Quality case coloring should provide cosmetic enhancement without endangering gun integrity or shooter safety....Be careful if you are contemplating sending your prized shotgun's receiver to a high heat bone charcoal mechanic.. He is going heat it up to around 1500 degrees F... Make sure that you get it in writing, that if the receiver warps in the heating and tempering process or that if it cracks after firing, then the mechanic will assume full financial responsibility for the destruction of your gun and/or your personal injury.
A low, controlled heat process, combined with specific chemicals is the safest way to recolor a shotgun receiver. So long as the heat is kept low and controlled, the original receiver metallurgy and heat treatment is not changed. No harm is done to the gun nor is there any potential for danger to the shooter, as a result of the re coloring process.
In summary, shotgun receivers should never be rehardened in the vain interest of restoring the cosmetic effect of case colors. Case hardening is a high heat process which alters the surface molecular structure of the receiver metal. Rehardening a receiver can warp it. Subsequent efforts to straighten the metal, either by bending or filing can only harm the fine original metal-to-metal fit and adversely alter the workings of carefully aligned internal shotgun parts. In addition, if the receiver surface metal is not correctly retempered after the hardening process, then the receiver metal may be too brittle and as a result, may crack upon firing.
Ed, Have you not ever seriously considered, in the face of such overwhelming opposition to your views, and with absolutely no supporting posts from others, that YOU MAY BE WRONG! ? "There is a way that seemeth right unto a man, but the end of which is destruction"......Proverbs 14:12 SRH
May God bless America and those who defend her.
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ed's descriptions show a considerable lack of understanding of steel metalurgy.
point - case hardening has almost nothing to do with strength and a lot to do with preventing wear. Bone charcoal CC'ed receivers will be low carbon steel. If a receiver is not adequately strong before hardening, it will not be strong enough after hardening. The engraving on a soft receiver will wear away quickly compared to the engraving on a cased receiver.
point - the colors and the hard case are fundamentally independent of each other. Steel can be case hardened without colors and it can be colored without hardening.
point - the colors are aesthetic, not structural. Note that guns continue to function as designed long after the CC is worn away. It is well known how to produce generic case coloring. However, the accurate reproduction of CC specific to a maker, trade, time period, etc. is very difficult.
DDA
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Hi
I know that this can be an extremely fiery subject no pun intended so just to add another slant on the colour case hardening theme, it has been a sort of life long interest of mine to collect now no longer used Brit Engineering oddities.
I won’t bore you with the details how I came across this method of colour case hardening.
Here in Britland during and just after the end of WW2 all sorts of products where in extremely short supply or just not possible to get hold of included in this where engineering sundries of all kinds.
Now just to put things in order during and just after the war the Government encouraged us Brits to grow vegetables in our gardens, yes it is true we are a nation of garden lovers even today and I include my self. Well that being the case garden products where not hard to obtain at all in fact rather a lot of it about and one in particular was a fertilizer known as Blood Fish & Bone (That is exactly what it is). Which is still used here today in quite large quantities in what we call “organic gardening”, well an enterprising company used this product mixed with redundant Gas Mask charcoal to make their own colour case hardening product. I was assured it worked extreemly well and was shown a Micrometre trial piece that had been processed using this mixture and it had extremely passable case hardening colours. They do say “necessity is the mother of invention” at the same time our German cousins where using a standard Nitrate based fertilizer to Nitre Blue steel!!!!
The only lessons in my life I truly did learn from where the ones I paid for!
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In Roy Dunlaps book "Gunsmithing" which as I recall was originally written in the 1950s he gave a formula for mixing a hot salt bluing solution using Ammonia Nitrate fertilizer & Lye. I tried a batch of it once & it did give an exceptionally good blue. It had a lot of sludge in the tank & was not very efficient to use due to that. It was Economical but apparently the inert portion of the fertilizer I used was different from what he had used as he did not report any problems in that regard.
Miller/TN
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Miller,
You are a trove of information.
Pete
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I remember a cute little paragraph in one of MacIntosh's books (I'm nearly sure) about a story in a London pub near the Gun Quarter ,about some old Gunsmith cch'ing an action by wrapping it in newspaper, well drenched in his "filtered ale" & then stuffing it in the middle of a good hot coal fire?...he didn't report how it turned out..:)...maybe he could vary the colours be changing brand beer??
It is fascinating how it works..colours are so nice.
franc
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You don't say whether or not the beer had been "processed" first...
No matter. Urine good company.
And you've given ed good a new idea!
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You don't say whether or not the beer had been "processed" first...
No matter. Urine good company.
And you've given ed good a new idea! And was it ale, dark, or light ? More research is needed me thinks.... Interesting thread,,,, bottle or can ?
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"Filtered" indicateds "processed," IMO. Further, IMO, I suspect there is at least one true incident of a CC'er "peeing in the quench water." IMO, this was his subtle hint as to what he thought of you request for disclosure of his secret (and successful) process. But, I could be wrong.
DDA
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I believe it is a pretty well established fact that at least one Southern Armory during the "War of Northern Aggression" had people save their Urine & bring it in, from which the procured the Saltpeter (Potassium Nitrate) they need for making powder.
I have also heard of the practice of mixing some Saltpeter in the quench water for CCHing for the purpose of releasing Oxygen to produce better colors.
I am not enough of a chemist to know for certain but perhaps peeing in the tank would produce a similar affect, but I'll leave it to others to find out.
Miller/TN
I Didn't Say Everything I Said, Yogi Berra
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Still wondering how cyanide works to color steel. Seems a common practice on the Continent. What's the chemical process and is heat involved?
Don't worry, I wasn't going to try this at home.........
The only constant in life is change.
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From my internet notes...
"Some color case hardening is done in the Vat method, Stevens and others used this method. It is called Cyanide. Cyanide is a salt that when heated up to about 1600 degrees or so anneals what ever is put into it and then hardenens it. It goes from the cyanide bath to a water quench. The Stevens got there ripple effect from a chain that was used to lower the parts into the bath and pull them up, supposedly the cog wheel the chain ran in helped make the pattern as it stopped momentarily at each cog. There is a company in Wyoming that uses this method with nice results. Not something you can do at home."
"Signal Mountain Gun Works uses an abbreviated potassium-cyanide based process for color case hardening. Browning/Winchester uses the company for their firearms since the receivers are already sufficiently hard (SAE 4140 steel heat-treated to a hardness of RC 38-42) and case colors are the main goal. Since case colors are the main objective (not a thick hardened case) the potassium-cyanide bath is heated to 1215 to 1225 degrees and the parts are left in only 5 to 10 minutes. I understand that a much thicker case can be achieved using the same process, but the temperature is increased to the range of 1400 to 1650 degrees and the parts are “soaked” for at least an hour, usually longer."
So to sum up they use heat and Potassium-Cyanide salts. I am sure the fumes are vented most likely after some type of conversion to harmless state by a catalytic conversion process and all workers around must wear breathing hoods and chemical barrier type clothing. Plus I suspect the EPA might become your best neighbor and constant companion. Even skilled amateur should let the pros handle this one.
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Thank you KY Jon. I wondered how it was done. It seem from your description that the potassium cyanide at the higher temperatures would impart some surface hardening to the metal as well.
Other than a difference in the color patterns, are there any functional differences in cyanide salt and bone charcoal processed metal?
The only constant in life is change.
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Have been searching without success to confirm: 1. Charles Jerred was briefly blinded by an accident using cyanide for case coloring at Hunter Arms. The Fulton guns were colored with cyanide rather than bone charcoal. Bro. Tom probably knows. 2. An English gunmaker was found dead in the basement of his shop, presumable from the fulminate of mercury he was using to make percussion caps or primers. William Eley? http://newsgroups.derkeiler.com/Archive/Rec/rec.pyrotechnics/2005-12/msg00095.html
Last edited by Drew Hause; 05/27/13 03:23 PM.
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A few terms that need to be understood. In heat treating parts which are to be hardened, are hardened to their maximum attainable hardness by being heated above their critical temp & quenching to cool them suddenly, the actual quenching medium depending upon the actual alloy. If this max hardness is not what is desired (Usually isn't) then they are tempered to bring them down to the desired hardness range. The higher the tempering temperature the softer the result. Charcoal & Cyanide are essentially two carbon bearing substances which when the part is heated above that critical temp the carbon is absorbed into its surface. The longer it Soaks at that temp in the presence of the carbon the deeper it penetrates. However the deeper it goes the longer it takes to go further so there is a more or less practical limit to the depths achievable. An alloy steel such as 4140 is seldom case hardened or colored. These steels are most often simply heat treated. They are quite often used for parts requiring high strength & the temps for coloring cannot be higher than the tempering temperature to which they were heat treated. I worked a few tons of 4140, 4340 etc in my career as a machinist & seldom died we temper it higher than around 900°F. Coloring it by cyaniding would be a specialized process not used too often in my opinion. Thos last two digits in 4140 denote approx 40 points carbon, case hardening is normally done on steel with a max of about 20 points carbon.
Miller/TN
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I don't believe cyanide case color hardening was or is all that rare. I think it was a cost effective manufacturing process and not reserved for higher end guns and rifles. Chances are millions of H&R Toppers had their receivers finished that way. I believe it's the current 'normal' receiver finish at Shiloh Sharps and pack hardening is an extra cost option.
I also believe alloys that can through harden, such as 4140, are regularly case colored, because I suspect that's what the market wants. I think many of us have seen tons of case colored Rugers, or imported single action revolvers and lever rifles with the look. I suspect the larger case coloring houses are called on to color 4140 regularly.
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I believe that CSMC RBLs are made of 4140 and many of them are colored, but I couldn't say how.
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Cyanide is not an element, but rather a compound which consists of a carbon atom triple-bonded to a nitrogen atom. As others have stated above, it is the carbon which bonds to the iron. Think of it this way. The iron forms a set of boxes all bonded to each other. Given the right conditions, a carbon atom "slips" into the box. This has the effect of producing a "harder" metal. The key is to prevent the iron atoms from bonding with oxygen during this process. If they do, all you have done is to produce rust. That is why, using charcoal or cyanide, the pack and quench are so important.
If I recall correctly, when Dr Gaddy took SEM images of a case color harden piece, the depth was only a few atoms.
Pete
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Last year Connecticut Shotgun let one of the shooting TV shows do a segment on how they get their case colors. Kind of a generic presentation with not a whole lot of info, but the camera clearly showed the oven set to 1331*. I don't know if that had any significance, but if the parts were quenched at that temp, there would not likely be any ability to harden the surface or otherwise. The demo was on an over under receiver and it seemed to come out with the right look.
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Note that an un-heatreated piece of 4140 will be both harder & stronger than a piece of 1018. The 4140 has even far greater potential through proper heat-treating & tempering. I don't really recall the hardnes/Temper range for it, but seriously doubt a piece heated to over 1200°F will retain a hardness of Rockwell 40C. That it is strong enough for the mentioned uses is obvious for a piece of case-hardened 1018 was adequately strong. That 4140 will work for these conditions is simply testimony to its great versatility, but I can tell you for certain if Faux Colored parts were its major use it would be an extremely short time before it would be no-existent as an available alloy. Its greatest use is for high strength, heat-treated parts which does not include tempering it to 1200+°F.
Miller/TN
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The cost to do cyanide, versus charcoal pack, case hardening must not be much different for a small gunshop today. Ron's, in Oshkosh, WI, does both, and the cost is only $10 difference for a doublegun receiver.
SRH
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2-piper I do not dispute your points. You have most likely forgotten more about this than I have learned. But if the goal is to color alone is that not done at the lower temp.? Hardness is already inherent in the metal. The color is all that is needed with 4140. Other milder, softer metal could be hardened by longer time exposure at a higher temp. for what I understand from my notes. I doubt H&R used only 4140 steel in making all those single shot guns. I suspect they used an easier to work metal and then hardened it with a case color change as a minor side effect.
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Stan posted, The cost to do cyanide, versus charcoal pack, case hardening must not be much different for a small gunshop today. Stan, the process costs themselves wouldn't be much different, cyanide is cheap enough, but there are environmental and safety considerations that would add greatly to the expense. Safe storage, personal protection equipment, poisoning recovery kit, proper signage, and treatment of contaminated waste waters are all statutory requirements in UK, and from what I saw of cyanide handling in the US would be the same there. Hazarding a guess, I'd put the factory cost ratio of cyanide to charcoal at around 15: 1. How that translates into the final invoice is up to the individual gunsmith, but his operating costs will be much greater with CN. Eug
Last edited by eugene molloy; 05/28/13 04:08 AM.
Thank you, very kind. Mine's a pint
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molloy: then there are the funeral expenses to consider...
keep it simple and keep it safe...
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From the ASM Heat Treater's Guide
SAE 4140 Steel Tempering
Tempering
Temperature Hardness
Brinell Hardness
Rockwell Tensile
400°F 200°C 514 HB 55 HRc 297 KSI
500°F 260°C 477 HB 50 HRc 243 KSI
550°F 290°C 461 HB 48 HRc 235 KSI
600°F 320°C 444 HB 47 HRc 225 KSI
650°F 340°C 429 HB 46 HRc 217 KSI
700°F 370°C 415 HB 44 HRc 210 KSI
800°F 430°C 363 HB 39 HRc 182 KSI
900°F 480°C 331 HB 36 HRc 166 KSI
1000°F 540°C 293 HB 31 HRc 145 KSI
Data extrapolated from a hardness graph given in Brinell with nearest points taken from a conversion table for Rockwell hardness. Temperature conversion to Celcius rounded to nearest 10°. Tensile not specifically for 4140. All data +/- 10%
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To add some perspective to the data above...my experience suggests that many modern firearms that are made from 4140 are hardened and tempered to around the low to mid 30's HRC (hardness) giving an ultimate tensile strength from about 145,000 psi to 165,000 psi. Mild steel has an ultimate tensile strength of about 64,000 psi. Case hardening is in the order of .003-.007" and does not change the core strength. Yield strength numbers are lower for both.
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good: you may add chemical processing to metallurgy in the list of industrial procedures of which you know little.
Accidental fatalities from the industrial use of cyanides are diminishingly rare. In 40 years of handing and transporting and the stuff in quantities from microgrammes to hundreds of tons I never saw or heard of one.
Thank you, very kind. Mine's a pint
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Mr. Molloy, for making that statement above, I think a lot of us would love to buy you a pint (beer, not cyanide!) should you ever visit the U.S.
A true sign of mental illness is any gun owner who would vote for an Anti-Gunner like Joe Biden.
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Not to be a bore, but within the plating industry, cyanide poisoning is a real risk.
Note to self: Should you be visiting a plater regarding the recoat of your Chrysler Imperial bumpers, and smell violets, skeedaddle.
Out there doing it best I can.
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Stan posted, The cost to do cyanide, versus charcoal pack, case hardening must not be much different for a small gunshop today. Stan, the process costs themselves wouldn't be much different, cyanide is cheap enough, but there are environmental and safety considerations that would add greatly to the expense. Safe storage, personal protection equipment, poisoning recovery kit, proper signage, and treatment of contaminated waste waters are all statutory requirements in UK, and from what I saw of cyanide handling in the US would be the same there. Hazarding a guess, I'd put the factory cost ratio of cyanide to charcoal at around 15: 1. How that translates into the final invoice is up to the individual gunsmith, but his operating costs will be much greater with CN. Eug I read you Mr. Molloy, but for whatever the reason, the reality is that he charges $260 for bone charcoal pack and $270 for cyanide. http://www.ronsgunshop.com/pricing.html Go figure, eh? SRH
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Chuck;
thanks for posting the tempering scale.
KyJon;
To now answer your question, this scale pretty well sums up my thoughts. You will note the highest tempering temp this scale went ot is 1,000°F which produces a hardness of about 31Rc. To twmper at 1200°F or above is going to drop that hardness well down into the Rc 20s. This is simply not a good use of 4140. 4140 is a great steel, but if I had a gun frame made of it I would want it given a proper heat treat & blued, just forget the color. If one wants color then use a grade of low carbon steel & case harden it. This gives the advantage of that "Glass Hard" skin which is wear resistant. You will definitely feel a difference in working a dropping block action or closing a double which cocks the ejectors by pushing them in as they rub down the breech face, between that hard case & a part in the Rc 20's. 8620 is a more modern alloy which I understand has a much higher strength than the old standard 1018 etc.
Miller/TN
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I agree with 2-p that there is little reason to use a plain low carbon steel alloy (like 1018 - 99.82% iron and 0.18% carbon and th th th th that all, folks, nuttin' else in there) for a modern gun action. There are modern alloys that are better and can still be case hardened. If, however, you are a traditionalist, you can use 1018 with confidence. The case hardened low carbon steel receiver has withstood the test of time for sporting arms.
DDA
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I'm curious as a lab in a chicken kitchen about the steps, temps and resultant core hardness that Doug Turnbull and Brad Bachelder get on the Parker Repro when they charcoal colorcaseharden.
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So 2-piper is it possible to color and not harden with a cyanide process and is it at a temperature low enough to not soften the metal (4140) too much? And I agree that with 4140 I would rather have a blue receiver. But some insist that case color is a must. Personally I find most cyanide colors to be too brash.
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Jon;
I don't really know that much about what all can be done with the Cyanide process. To harden though requires the part be above its critical temperature prior to quenching. Even presuming that Cyanide can be used to produce color below this critical temp, it would still I suspect require a temp much higher than I would want to submit a gun of mine to, whether a low carbon or higher carbon alloy steel. Either way you are going to end up with that soft surface.
Miller/TN
I Didn't Say Everything I Said, Yogi Berra
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I think a good question would be how soft is too soft. Rifle barrels of 4140 for high pressure cartridges are typically listed as having a rockwell C hardness in the mid twenties. It may not even be possible to treat 4140 to be much softer than that.
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Clapper Zapper posted Not to be a bore, but within the plating industry, cyanide poisoning is a real risk. CZ, It might be more accurate to describe it as a hazard rather than a risk in modern plating shops. A hazard only presents itself as a risk when you don't do anything about it. Given the established and recognised methods of handling cyanides, there is very little risk of anything nasty happening. As I said fatalities from accidents are virtually unknown. Most plating shops stink anyway; violets would be a great improvement! I always thought CN smelled of marzipan or almonds, and to this day I loathe both. Some cyanide plating processes when running hot give off ammonia, and I'm not overly keen on that either!! Eug
Last edited by eugene molloy; 05/30/13 09:22 AM.
Thank you, very kind. Mine's a pint
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I think a good question would be how soft is too soft. Rifle barrels of 4140 for high pressure cartridges are typically listed as having a rockwell C hardness in the mid twenties. It may not even be possible to treat 4140 to be much softer than that. All true; Of course if rifle for high pressure cartridges happens to be a bolt action if the steel for the bolt lugs & their seats in the receiver were of that same mid-twenties Rc hardness it would be only a few shots until it had developed Dangerously Excessive head space. Both the steel & its treatments need to be selected according to use. I will simply say, that to the best of my knowledge the older doubles made of low carbon steel were "Proofed" In The White. That even in this form they were adequately strong is evidenced by the fact they passed. They were however "Not" left in this condition & for a reason other than just the colors. "IF" I had a frame made of 4140 as long as it was in my possession it would "NOT" intentionally be exposed to temps in the 1200°F range. Nuff Said.
Miller/TN
I Didn't Say Everything I Said, Yogi Berra
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Sorry about that Miller, I suspected it could be taken as argumentative, but it was just an illustration of one way 4140 is used in gunmaking.
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Eugene, Please don't interpret my comments in any offensive manner.
If you acidify even if by accident any small quantity of the common CN salts, you create an exposure risk of some severity. Not to mention essential safe handling requirements of the salts themselves.
Our OSHA specifications for nitriding with CN compounds are pretty strict. And very expensive to implement.
Out there doing it best I can.
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Is there any difference in the durability between cyanide and bone and charcoal? I understand the Savage 311 is cyanide treated. I have had one since I was in my teens and have used it extensively for over 35 years. It seems there is very little wear of the colors on the receiver however the blueing on the trigger guard is well worn.
Nothing is foolproof to a sufficiently talented fool.
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The last conversation I had with Dr. Gaddy we discussed the possibility of coloring in the 600 - 800 F range and thought it could be done. Note that the color has to do with the thickness of the coating. Note that temper colors start to appear in the 400 F range and are done by 650 F. Temper colors seem to be films of relatively pure iron oxide whereas CH colors seem to involve more complex compounds via the "impurities" in the quench.
I don't know if anyone has tried forming CH colors at reduced temperatures, but I'd surely like to know if anyone has, suceed or fail.
DDA
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A low, controlled heat process, combined with specific chemicals is the safest way to recolor a shotgun receiver. So long as the heat is kept low and controlled, the original receiver metallurgy and heat treatment is not changed. No harm is done to the gun nor is there any potential for danger to the shooter, as a result of the re coloring process.
keep it simple and keep it safe...
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Ed...will you ever give up ?
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This is a perfect example.
Of why this BSS is populated by a host of unassailable experts.
Not.
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Well please enlighten us.....your contributions to the board have been quite deep so far. Maybe some more snide comments to show the depth of your knowledge on the subject? Sitting on edge of my seat waiting to learn more from you.
Steve
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We nitride pump housings for wear resistance, and strength improvement. Without secondary machining operations. Finished soft parts go in, wear resistant parts come out. Does that sound like a cheap shotgun to anyone? Here's a link to a decent, concise article, that shows most of the blank spots in this discussion. http://www.iaeng.org/publication/IMECS2011/IMECS2011_pp1244-1247.pdfFWIW, Casenite(sp) changed it's formula a few years back to a "safer" mixture. Should a person have a can of their old formula, you could re-create the article above.
Out there doing it best I can.
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I don't have any idea of how old a can one would have to have but upon my first introduction to casenit some 50 years ago it has always been stated to be Cyanide Free. I have also seen references to, but never further investigated, that one of the chemicals used in film development could be used in the same manner as Casenit.
For those not familiar with temp conversions those temps given in the referenced article in "C" convert to 1454°F to 1688°F.
It should be noted that heating in this very same bath to 1200°F, while it may give a good color will not harden the part but will in fact draw its temper very close to its fully annealed condition.
Miller/TN
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A low, controlled heat process, combined with specific chemicals is the safest way to recolor a shotgun receiver. So long as the heat is kept low and controlled, the original receiver metallurgy and heat treatment is not changed. No harm is done to the gun nor is there any potential for danger to the shooter, as a result of the re coloring process.
Having read your vague, non-specific spiel a good number of times throughout the various color case hardening threads, I want to better understand what you are talking about when you say "specific chemicals" and "low controlled heat". Are you talking "color" restoration with cold blue chemicals, temper colors enhanced by salts, water color paint, what chemicals are you talking about? How low and controlled of a heat are you talking about? Room temp, 250F, 500F? Applied with a torch, furnace, easy bake oven? Light yellow on steel doesnt start showing up until about 400F and blues and purples dont show up until about 550-600F, how are you achieving color without heating to at least those temps? Unless its a room temperature application I think you are incorrect about your process not affecting the metallurgy, especially if the heat is applied to selective locations via a torch. Do you really believe that your low/controlled chemical process is better and safer than the original process that hundreds of manufacturers over the years have used as their standard for heat treat? Are you really worried that all the major restoration shops today are producing dangerous work via "High-Heat" color case hardening? The reason I ask is because I grew up in a gun shop restoring guns and later worked for a well known gun restoration shop throughout college and I have color case hardened hundreds of guns via the traditional bone and wood charcoal method. When I hear things like "specific chemicals" and "low-controlled heat" I cant help but to think what BS that is. I read that as an amateur gunsmith reading the Ithaca-Perazzi manual wiping cold blue all over a receiver. I actually found that with many restorations the receivers were superficially case hardened from the factory to begin with due to what I believe was the guy at the furnace "eyeballing" the crucible color. Other receivers were quite hard in comparison, especially some L. C. Smiths from what I remember. By todays standards the color case hardening process used by all the major manufacturers to heat treat their actions was an imprecise crap shoot. Funny thing is, for how comparatively imprecise it was we rarely see a cracked frame to this day, but we do see a good number of loose guns. Overall I think the low/controlled heat chemical process you promote is more dangerous to receivers than the modern, precision controlled bone and wood charcoal (original factory standard) of years past does. Channing Will
Last edited by CMWill; 05/31/13 11:53 AM.
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joe: after appomattox, some of my ancestors left Alabama and went to brazil. some stayed. some came back. none ever gave up the cause, so far as I know...
and with rare exception, recase hardening a shotgun receiver lessens the value of most guns...this is due to the unknown quality of the receiver metal after it has been subjected to the rehardening process. turnbull and delgrego case hardening work seem to be the most accepted in the market place, with batchelder coming on strong in the stretch...sadly, many buyers are concerned more with looks than function.
keep it simple and keep it safe...
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cm: please reread the narrative I posted earlier in this thread. it will answer some of your questions regarding the difference between factory case hardening and after market re case hardening. a low heat, chemical process is not case hardening. it is case coloring, in an effort to simulate factory receiver case colors. unlike recase hardening, the low heat, chemical process does not disturb the original factory receiver metallurgy, and hence poses no danger to the gun or shooter...
and please note, i do no gunsmithing work of any kind. i have little specific knowledge of case hardening or case coloring. tony treadwell's book is the best description of the recase hardening process that i am aware of...my approach to all of this is as a hobby gun dealer. if enhancement increases the value of a gun and makes it more sellable at a higher price...great! if not, then don't do it.
Last edited by ed good; 05/31/13 12:14 PM.
keep it simple and keep it safe...
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...i have little specific knowledge of case hardening or case coloring.....if enhancement increases the value of a gun and makes it more sellable at a higher price...great! In summary, shotgun receivers should never be rehardened in the vain interest of restoring the cosmetic effect of case colors. ...unless you are trying to re-sell them?? If you think "enhancements" that increase value are good for sales, why do you then go on to condemn re-color case hardening in "vain interest of restoring the cosmetic effect of case colors"? Lets say you purchased a used Parker shotgun and the receiver has been blued by some idiot. You would rather take that action, polish it in a hardened state, and then add imitation case colors with a low heat chemical process that is nothing like what the factory ever produced just to re-sell it at an "enhanced" value? That would be like installing a Pleather covered recoil pad and calling it Leather. If you admit to having little knowledge of case hardening and case coloring subjects why are you constantly chiming in on these threads?
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cm: your posts are starting to get some what confrontational. however, I am trying to keep my responses civil...in an earlier post, I listed three firms that do re case hardening in order to achieve factory like case colors...in my opinion, these three firms have established themselves as experts in the field. whats more, the cost of their work is often recoverable come resale time, but not always. if you have work done to a gun, you should keep the receipt as proof of who did the work. otherwise, it is just another redone gun and worth typically less than if you have proof of who did the work.
as to your parker example, much would depend on the grade and gauge of the gun and what else needed to be done to it in order for any enhancements to make economic sense. wish it was simple, but it is not, particularly in this continuing stagnant economy of ours. buyers and sellers for profit, have to be very diligent and should guard against rapidly changing markets.
although I have little knowledge of refinishing processes, I have lots of experience trying to recover consigner investments in poorly done refinish work. even the cost of well done refinish work is sometimes difficult to recover, particularly if an item was not worthy of the expense to begin with or the work is undocumented. the best rule of thumb I can give you is this: if it is likely that the cost of enhancement will increase the value of the item enough to make a profit, then consider it. if not, or you are not sure, then don't do it. the expense of recase hardening is rarely recoverable. and the risks to damaging the receiver are considerable, regardless of who does the work...this may be why the experts charge so much?
keep it simple and keep it safe...
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My apologies, I am not aiming to be confrontational. I thought you could shed some light on the subject since you often suggest people should use the low temp controlled chemical process rather than traditional method. I worked for one the three firms you listed and appreciate your rule of thumb regarding restoration, but I can assure you the cost is not related to any risk of damage. The cost is related to the hours it takes to disassemble, clean, anneal, polish, chase engraving, prep and process the parts, reassemble, etc. Send in a prepped part and the process usually cost a couple hundred bucks, not much more than regular bluing. I think with any restoration you will be much better off choosing the original factory processes, thats jmho.
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cm: regarding original factory heat treating processes as compared to re case hardening, when a factory heat treated a receiver the metal started out soft and to a known spec as rolled or cast or perhaps annealed to a known spec.
an after factory re heat treating process starts with a receiver that has already been factory heat treated to a known spec. as I understand it, the first step in the re heat treating process is annealing, which destroys the original factory heat treatment of the receiver. step two is coloring, via cooking the receiver above critical temp in a high carbon environment. step three is rehardening the surface of the receiver metal via a quench. and finally step four is tempering the metal back to a less brittle, more elastic state. much of the specs used in re heat treating processes are developed by trial and error, as much of the original factory heat treating specs have been lost...what works for one brand of shotgun receiver, does not work for other brands. and as I understand it, what works on say a parker receiver, vintage 1880, will not necessarily work for a parker receiver, say of vintage 1935, and so on. the tricky part seems to be the tempering step. this is where many inexperienced case hardening mechanics go astray. as you have worked for one of the more successful firms engaged in re case hardening, I would be interested in hearing about your experiences.
as previously indicated, a low heat, chemical process recolors the receiver only and does not change the original factory heat treatment of the receiver... some like the appearance of chemical induced case colors. some do not...perhaps it is best to just leave a fine old gun alone and let it be as is? but, if you must recolor, it makes more sense to me to not mess with the functional parts of the gun, particularly the receiver. better to keep it as originally manufactured and avoid the unintended consequences of reheat treating receiver metal.
Last edited by ed good; 05/31/13 08:45 PM.
keep it simple and keep it safe...
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As Yogi said, "It's like deja vu all over again" Back under my rock.
RMC
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cm: regarding original factory heat treating processes as compared to re case hardening, when a factory heat treated a receiver the metal started out soft and to a known spec as rolled or cast or perhaps annealed to a known spec.
as previously indicated, a low heat, chemical process recolors the receiver only and does not change the original factory heat treatment of the receiver... some like the appearance of chemical induced case colors. some do not...perhaps it is best to just leave a fine old gun alone and let it be as is? but, if you must recolor, it makes more sense to me to not mess with the functional parts of the gun, particularly the receiver. better to keep it as originally manufactured and avoid the unintended consequences of reheat treating receiver metal. 
Doug
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well then, buy all means fire up the furnace and start cookin dem receivers... http://wn.com/what_is_case_hardeningthe video where larry cooks that old parker receiver is particularly interesting. wonder if he had any trouble putting that gun back together?
Last edited by ed good; 06/01/13 10:22 AM.
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I wanted to add this because Miller's point about temper when re-casing is important.
This is from a Table on "The Working of Steel" located within the Gutenberg Project, 1920ish Metalworking manual.
Techniques based on the technology of the time.
TABLE 23.—TEMPERING TEMPERATURES FOR STEELS
Temperature
for 1 hr. Color Temperature
for 8 min. Uses
Deg. F. Deg. C. Deg. F. Deg. C.
370 188 Faint yellow 460 238 Scrapers, brass-turning tools, reamers, taps, milling cutters, saw teeth.
390 199 Light straw 510 265 Twist drills, lathe tools, planer tools, finishing tools
410 210 Dark straw 560 293 Stone tools, hammer faces, chisels for hard work, boring cutters.
430 221 Brown 610 321 Trephining tools, stamps.
450 232 Purple 640 337 Cold chisels for ordinary work, carpenters' tools, picks, cold punches, shear blades, slicing tools, slotter tools.
490 254 Dark blue 660 343 Hot chisels, tools for hot work, springs.
510 265 Light blue 710 376 Springs, screw drivers.
It will be noted that two sets of temperatures are shown, one being specified for a time interval of 8 min. and the other for 1 hr. For the finest work the longer time is preferable, while for ordinary rough work 8 min. is sufficient, after the steel has reached the specified temperature.
So why post this?
Because we see annealing ocurring in 8 minutes or less. At quite low surface temperatures. Also, remembering that case is quite thin.
One technique I have read about, but have never seen performed, would be to electro plate the part with a heavy layer of copper. Shielding from plating areas that re-casing might be desired. Then briefly re-casing for a shallow case, and then quenching in a bath of effervescence. Copper then removed.
Anyone ever heard of that?
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clapper: interesting, but please explain how this relates to heat treating of sxs shotgun receivers...
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The aesthetic appeal of case hardeing colors is a mystery to me, but to each his own. Does anyone know of a reliable way to hasten the fading of the blue-brown to the patina that is revealed after case colors fade? No, not the coin finished stage, but that soft grey which for my taste is about as good looking a metal surface as can be.
I tried steel wool, gentle abrasives but cannot get that soft sheen. I guess what is needed is some polite alternative to human sweat. Well, it is a better alternative to some other body fluids mentioned above.
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I'll confirm this with my best friend after he comes in off the lake, but in my view, "You can't get there from here."
If someone has a secret way to get a receiver from room temp to a colorable temperature, without going through the tempering zone, I'm all ears.
And No, Ed, I'm not talking about paint.
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lover: you sound like a Belgian. they don't like case colors either, but prefer a pewter like appearance to their shotgun receivers.
exposure to direct sunlight seems to naturally fade case colors. ever notice how many guns from texas and other places south are void of case colors?
you might try naval jelly or sodium hydrosulfide. they are both strong oxidizers...
keep it simple and keep it safe...
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clapper: watch larry's video referenced above. he preheats his oven to 1400 degrees before inserting his packed crucible...wonder what the heat curve looks like?
keep it simple and keep it safe...
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Ed- I've seen many videos related to heat treating. Larry P. jigs up everything he puts in the crucible. As many companies have consistent patterns on their colored parts, I'm pretty sure they shield their parts the same way every time, to get the color pattern they desire.
My only real curiosity about this anymore is "Can patterned oxides (and other films) be created at the surface of a previously case hardened part, without the carbon atoms beneath the film migrating out?" I'd need to see sections from a sacrificial part to develop my opinion.
Please read the MSDS, Kasenit is a mixture of Carbon black, and Ferro Cyanide compounds.
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...."Can patterned oxides (and other films) be created at the surface of a previously case hardened part, without the carbon atoms beneath the film migrating out?".... I wonder if the carbon left at all. I thought the environment in the pack, to create the colors, is carbon (CO?) rich and blocks oxygen. You'd think the surface might pick up a tad more carbon if colors show up.
Last edited by craigd; 06/01/13 01:02 PM. Reason: typo
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lover: you sound like a Belgian. they don't like case colors either, but prefer a pewter like appearance to their shotgun receivers.
exposure to direct sunlight seems to naturally fade case colors. ever notice how many guns from texas and other places south are void of case colors?
you might try naval jelly or sodium hydrosulfide. they are both strong oxidizers... Yes prolonged exposure to UV will have a negative impact. HOWEVER, we are talking years. Why anyone would not at least use a case is beyond me. Case coloring will fade because of handling. Why any idiot would put naval jelly on a new gun is beyond me. Naval Jelly is infused with phosphoric acid! Those "Texas" guns had obviously been heavily used and handled. That "pewter" appearance can be achieved after a gun has been hardened by removing the case colors with toilet bowl cleaner aka dilute Hydrochloric acid. It is called a French finish. Ken Hurst uses that "trick". Or simply have the metal recase hardened using a product like Kasenit. Pete
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Don't confuse Cyanide processing with Charcoal pack processing.
I'd love it if someone would just make a PE showing .5 in thick pieces case hardened, representative samples sliced and polished, and then re-cased at an agreed apon temperature for the purpose of coloring. Finishing with slice and polish, and measuring of the case after round 2. Just think how boring the vintage machinery and gun sites would then be.
That would tell us more than we wanted to know.
I read an additional article from way back about japanning the pieces to shield them when re-coloring. A paint on protectant might be much easier than Cu plating for round 2.
Latest guys to get poisoned around here were stripping stolen X-ray film in a garage. Some others were rendering the gold from recycled computer parts.
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Ed and Pete thanks for the pointers. A friend has an old H&H that lost its case color, the surface is an even grey patina that gives that shotgun a lot of character. I will try the weak acid on an old piece and see what happens.
I have used naval jelly to remove bluing before but never on case colors. Will give that a try too and see how it works.
Last edited by Shotgunlover; 06/02/13 06:12 AM.
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Clapper Zapper posted One technique I have read about, but have never seen performed, would be to electro plate the part with a heavy layer of copper. Shielding from plating areas that re-casing might be desired. Then briefly re-casing for a shallow case, and then quenching in a bath of effervescence. Copper then removed. Anyone ever heard of that? Pretty common currency in Birmingham around forty years ago; we used a cyanide copper bath. I'm not exactly sure what the following heat treat process was, that wasn't our bag, but it wouldn't have been charcoal; almost certainly gas carburisation. Where edge nodulation occurred the copper had to be machined back to a datum surface, so there was a lot of toing and froing which made it very expensive and thus suitable only for "special" high value parts. Usually applied to seriously big parts that needed crane hoists, from memory the deposit was around .050", but we went over that quite a bit on occasion. Eug
Last edited by eugene molloy; 06/02/13 07:29 AM.
Thank you, very kind. Mine's a pint
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PeteM, or anyone, can you explain the sunlight fading mechanism? I can't find anything about the "stuff" that makes up the CC film that "should" be photoreactive. I had a long talk with Dr. Gaddy about this and his opinion was it is not photoreactive. I. too , have heard often CC will fade in sunlight, but as of now, I'm a skeptic.
DDA
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...."Can patterned oxides (and other films) be created at the surface of a previously case hardened part, without the carbon atoms beneath the film migrating out?".... I wonder if the carbon left at all. I thought the environment in the pack, to create the colors, is carbon (CO?) rich and blocks oxygen. You'd think the surface might pick up a tad more carbon if colors show up. I can't think of any reason why the carbon would leave the case and participate in the colors. The colors, AIU, involve oxides of iron and other stuff in the quench, not carbon. DDA
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Don,
I seem to remember a long discussion about this that took place here many years ago. I can't find the post. Apparently I did not save the thread in my archives.
So, I guess I was repeating what I can't back up. After a web search about the effects of UV, I cannot justify the notion of fading having an impact on case colors.
Perhaps some one with practical experience can help.
Pete
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Don,
I seem to remember a long discussion about this that took place here many years ago. I can't find the post. Apparently I did not save the thread in my archives.
So, I guess I was repeating what I can't back up. After a web search about the effects of UV, I cannot justify the notion of fading having an impact on case colors.
Perhaps some one with practical experience can help.
Pete Years ago on a thread on this BBS, I brought up the fact that UV fades the case colors, and many key board engineers argued as many normally do and disagreed vehemently .......It is common knowledge with people who have practical experience with case colors as guns are brought in that are faded from years of UV exposure and without normal handling wear/carry patterns on the bottom of the receivers, this fading does occur normally from both natural sun light and indoor florescent lighting. Ken Hurst finally chimed in on that same thread and agreed also, noting that Colt, where he worked for years as an engraver, had a problem with the UV from florescent lighting fading the case colors in their show room on new guns , so Colt would remove and replace the faded CCH guns every year, which were faded on the UV exposed upper side only and they would re-case them........ But many of you still argued endlessly because you couldn't find some Phd's paper on the internet referencing this subject......but I can tell you for a fact that UV fades case colors......and it is well known with people who work with CCH-----NO, it's not overnight, but UV fades case colors.......the old glass doors on wood gun cabinets were famous for reflecting sunlight and fading case colors on either the morning or afternoon sunlit sides only...... As Wonko says, have a day.......
Doug
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What's the issue? These films are very complex chemistry, locked into unstable crystal structures at quench via fast cooling. Some are stable, some are weak, some are brittle, and they are microns thin. They lay over each other like potato chips. Some are stuck to the base material more strongly.
Energy of any form will release some of these structures from their temporary state. Rubbing, UV, solvents, heat, they'll all break the potato chips.
At some point they have to equilibrate. But if you are vibrating atoms with UV energy, some are going to move around.
No one ever mentions it on these discussions, but quench chemistry can be very exciting stuff.
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What's the issue? These films are very complex chemistry, locked into unstable crystal structures at quench via fast cooling. Some are stable, some are weak, some are brittle, and they are microns thin. They lay over each other like potato chips. Some are stuck to the base material more strongly.
Energy of any form will release some of these structures from their temporary state. Rubbing, UV, solvents, heat, they'll all break the potato chips.
At some point they have to equilibrate. But if you are vibrating atoms with UV energy, some are going to move around.
No one ever mentions it on these discussions, but quench chemistry can be very exciting stuff.
I thought the Doc Gaddy articles showed the film to be relatively simple chemistry arranged in a unique way. The colored film that forms might not be so unstable, some colors show centuries later if they are protected. I'm not following what the temporary state is that is going to equilibrate. Aren't the colors primarily iron oxide and separate from the thin case of steel that was formed that may or may not be hardened. I don't think you need to quench to form iron oxide, but the quench seems to arrange the iron oxide in the way that shows as gun case colors. I think there are things that affect the appearance of the colors, but I think all that means is it isn't always the toughest most resistant surface finish not that it's tearing itself apart to release stress. Even after the colors are long gone, there could still be a hard steel case on the part.
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So an ideal way to remove case coloring and bring on that soft grey patina would be to take the action body and the forend iron to a tanning salon. Finally we have a legitimate reason for these places to exist!
Now that you mention it, on many faded old guns the only place the case coloring can be seen is the inside of the forend iron, the part that faces the underside of the barrels and is permanently shielded from the light.
Last edited by Shotgunlover; 06/03/13 04:30 PM.
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Craig, there are something like 1000 varied forms of Iron oxides. Bond lengths, angles, electron energy levels, quantum effects, all shape the molecules and their reflectivity. Some are short lived forms. Every molecule desires to return to it's laziest condition. The quench can confine? molecules in an "anxious" condition. And they await an opportunity to go to a lower energy state. Sometimes the energy hump to cross is quite high, and sometimes not. Might even have 2 or more humps.
I don't think people are all that interested in coordination chemistry when they just want a pretty blue color.
I know there are many that do not believe in this stuff. But I am in the camp of colors transforming. They seek a lower energy level.
I am reminded of the effort to grow cubic tomatoes, to expedite packing.
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I'm saying CC can't be photoreactive, but I am open to hear some chemistry to explain how it is reactive. Metals and metal oxides, far as I know, do not tend to photoreactivity. "Rusty" steel does not fade from loooong exposure to sunlight in my experience. The colors in CC are created by the thickness of the "stuff" layers. Thinner layers create yellows, middlin' layers make reds, and thick layers are blue to purple. Did I get that right? The actual light is reflected by the steel surface, but wave lengths other than the color we see are absorbed. Actual thinning of the "stuff" layer should, then, change the color, not fade it. Fading would, in my estimation, happen as the various areas wholesale loose their layers. So an area missing half of its "stuff" layer would be less bright than one with 100% coverage. Note how thinning bluing becomes less "bright" compared to fresh, 100% blue. This logic says that you don't wear off some of the outside of the layer, but loose the "chips" in a chip by chip fashion.
I'm not interested in proving this issue one way or the other, only in finding the truth. Looking forward to debate points to the above.
DDA
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Most of us tend to think of color as residing in pigment or dye. Iron oxide in common rust is a reddish pigment; white lead is a white pigment and so on. The very thin surface layers that cause case colors are indeed very thin as noted above by Rocketman. He is right when he says that the colors are caused by the thickness of the surface layers, but it isn't a build-up of pigment that does it, it's wavelength interference.
Light passes through the surface layers, hits the substrate and is reflected back. Specific wavelengths are interfered with; others pass through and which are interfered and which pass depends upon:
1. the thicknes of the surface layer
2. the refractive index of the surface layer
I have no idea if UV or other energy will change the refractive index of the surface layers but it indeed possible as Clapper noted. The light doesn't have to change the thickness (or amount) of surface layer, it would just has to change its refractive index.
When we think of terms of pigment it is obvious that a heavier layer will be more opaque or darker, but the colors resulting from interference are generated by a different process entirely.
Think blue jays (the bird). There is no blue pigment in their feathers.
Then think the colors (blue to yellow) that you see on the surface of camera lenses. These too are interference colors generated by the anti-reflection coating on the surface (magnesium fluoride etc). A magnesium fluoride coating 1/4 wavelength thick will look blue in reflected light.
The rainbow colors generated by a spreading oil droplet on a puddle of water is the same phenomenon - the colors are not intrinsic to the oil; they are generated by interference of the light reflected through the oil from the oil/water interface.
The holy grail in case coloring is finding a non-thermal chemical way to create the surface coatings of proper refractive index. Then one could renew case colors without risking the integrity of the metal.
Note added in edit: Worn case color seems to become grayish - that is consistent with physical thinning. This doesn't represent "fading" in the common sense, it is the result of a shift in wavelength interference. In physical thinning the refractive index of the layer stays the same but its thickness decreases. Thickest layers will produce blue interference; then as the thickness decreases we see purple, red, gold, silver and finally grey. For a layer with an index of refraction of 1.5 we see blue at about 220 millimicrons, grey at <60. Note that the index of refraction hasn't changed. If photreactivity changes the refractive index then that would be a separate mechanism whereby perceived color would change.
Last edited by Gnomon; 06/04/13 06:32 AM.
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I suspect the answer to these perennial questions is "all of the above". UV light degrades certain hues without mechanical contact, as pointed out by the display case observations. That is a simple enough experiment to perform. It implies a photochemical reacion.
I don't think this topic really needs to fall into either/or categories. Physics vs Chemistry.
The films composition and thickness can be changed by many things. It might be interesting to fire a shotgun a few thousand times in the dark, jigged so as not to touch the reciever, and then observe any changes. Chuck's hinge-pin discussion reminds me there's plenty of energy at firing to bend the action bars, and possibly disrupt the films. This would demonstrate brittleness I believe.
Then of course, there's just plain ole' oxygen, anxious to join it's Ferr(ous,ic,ite)brothers on the road to entropy.
Someone with a kiln could easily do experiment 1 at no significant cost.
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Gnomon, I believe the ability of an iron oxide layer to interfere with light wavelength, refract, etc. to cause different colors to appear is well known.
But, as Doctor Gaddy pointed out, the example of an optic lense or drop of oil might not be good analogies to gun finish colors. Those examples are true optic occurrences, the color changes as the viewing angle changes because the light coming into the eye has passed through a slightly different thickness of oil or lense coating.
Gun cases colors don't change to any appreciable amount when it's viewed at different angles.
ClapperZ, if someone had a kiln what easy experiment would you be considering to show the variety, complexity, reactivity and instability of gun type case colors. Does oxygen have an energy favorable drive to react with iron oxide that's already formed on the surface of a gun.
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Sidelock
Joined: Dec 2001
Posts: 6,304 Likes: 222 |
Rocketman, Dr. Gaddy once told me of a test he had done on several pieces of identical steel that he had case colored. One piece went to an area that received the most direct sun, another into the house somewhere and another into a closet. There may have been more samples. After a year or two, comparison of the pieces showed no difference in the colors.
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Joined: Jan 2002
Posts: 9,825 Likes: 101
Sidelock
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Sidelock
Joined: Jan 2002
Posts: 9,825 Likes: 101 |
"The holy grail in case coloring is finding a non-thermal chemical way to create the surface coatings of proper refractive index. Then one could renew case colors without risking the integrity of the metal."
another voice in the wilderness...
keep it simple and keep it safe...
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Joined: Jun 2006
Posts: 3,056 Likes: 338
Sidelock
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Sidelock
Joined: Jun 2006
Posts: 3,056 Likes: 338 |
I would color a bar, shield it with probably aluminum sheet on each end, and then expose the bar to high levels of narrow spectrum uv light until summers end. Pick your nanometer.
There is a continuous conflict between people that have observed fresh case coloring (without clear(ish) coatings) degrading in short periods of time, and those that say the surfaces are inert to light.
I suppose the bar could be laid in a tupperware box filled with argon or tri-mix to exclude oxygen.
I do not believe ferro-oxygen coatings are inert in our atmosphere. I believe there are great numbers of compounds captured in the films at quench, and some are very delicate. Delicate merely implying they can be changed in conformation or presence via outside energy, within the realm of what we might normally provide.
I worked in inorganic polymers during the cold war in an effort to protect carbon forms from neutrons. Even in the most extreme conditions, we had isomers, conforms, and stability issues.
I'm kinda glad it didn't work out, because ultimately it supported the limited use of atomic weaponry.
We should use this WWW of interested parties to cooperatively demonstrate, and collect these pieces like Drew and Pete have done for Damascus barrels.
Lots of deceased scientists findings have been refined and enhanced after their passing.
I used to have to re-do every experiment that came from a Russian publication. Even if it was re-heating H2O.(joke)
Out there doing it best I can.
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Joined: Feb 2007
Posts: 384
Sidelock
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Sidelock
Joined: Feb 2007
Posts: 384 |
Interesting thread, INMHO there are only two MASTERS of case colour hardening, St ledger in Birmingham, UK and Schilling in Austria. Doug Turnbull in the US is good but you have to ask for "subdued" colours, some of his stuff comes out looking like a rainbow ! Cyanide coloring I think looks poor, best Spanish gus get sent to St Ledger (as do Hollands, Purdey and Boss). The metallurgy of an action also dictates what can be done. I had a 6.5 x 54 custom rifle made from an old Greek military mannlicher, to see the whole story click on this link http://forums.nitroexpress.com/showflat.php?Cat=0&Number=126684&an=0&page=3#Post126684At the end we could not case harden parts of the action as the Rockwell measurements were off the scale  Still, interesting, best
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Joined: Jul 2011
Posts: 972 Likes: 10
Sidelock
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Sidelock
Joined: Jul 2011
Posts: 972 Likes: 10 |
Mike, I think you can add a third to the row of fine case hardeners: Max Ern is a Master Gunmaker here in Germany and his work is well known under the best gunmakers because he is doing their color hardening as well.... have a look: http://max-ern.com/english/bunthaerten.htmhere some examples just pictured:     Kind Regards, Wolfgang
Last edited by Gunwolf; 06/13/13 11:26 AM.
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Joined: Jan 2005
Posts: 390 Likes: 2
Sidelock
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Sidelock
Joined: Jan 2005
Posts: 390 Likes: 2 |
Interesting thread, INMHO there are only two MASTERS of case colour hardening, St ledger in Birmingham, UK and Schilling in Austria. Doug Turnbull in the US is good but you have to ask for "subdued" colours, some of his stuff comes out looking like a rainbow ! Cyanide coloring I think looks poor, best Spanish gus get sent to St Ledger (as do Hollands, Purdey and Boss). The metallurgy of an action also dictates what can be done. I had a 6.5 x 54 custom rifle made from an old Greek military mannlicher, to see the whole story click on this link http://forums.nitroexpress.com/showflat.php?Cat=0&Number=126684&an=0&page=3#Post126684At the end we could not case harden parts of the action as the Rockwell measurements were off the scale Still, interesting, best In the link to Nitro Express, your gunsmith mentions that he could do a French grey finish from almost in the white to charcoal. How would he do that? I know some scrub down a casehardened finish, but in your case that would not be possible. Thanks.
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Joined: Feb 2007
Posts: 384
Sidelock
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Sidelock
Joined: Feb 2007
Posts: 384 |
Mike, I think you can add a third to the row of fine case hardeners: Max Ern is a Master Gunmaker here in Germany and his work is well known under the best gunmakers because he is doing their color hardening as well.... have a look: http://max-ern.com/english/bunthaerten.htmhere some examples just pictured: Kind Regards, Wolfgang Gunwolf, true, that is very nice work, a new name to me , thanks, Mike
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Joined: Dec 2003
Posts: 78
Sidelock
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Sidelock
Joined: Dec 2003
Posts: 78 |
Gunwolf, Thank you for the brilliant photos. The guns look as good as any London best gun. The engraving is top notch. Could you please tell us more about Max Ern guns? I have been going through their website. Mike, I think you can add a third to the row of fine case hardeners: Max Ern is a Master Gunmaker here in Germany and his work is well known under the best gunmakers because he is doing their color hardening as well.... have a look: http://max-ern.com/english/bunthaerten.htmhere some examples just pictured: Kind Regards, Wolfgang
Whenever you find yourself on the side of the majority, it's time to
pause
and reflect.
- Mark Twain
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Joined: Dec 2001
Posts: 7,090 Likes: 465
Sidelock
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Sidelock
Joined: Dec 2001
Posts: 7,090 Likes: 465 |
Max makes the finest single shot break open rifles in the world IMHO. Top notch work all around and a very nice gentleman as well.
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Joined: Apr 2016
Posts: 726 Likes: 113
Sidelock
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Sidelock
Joined: Apr 2016
Posts: 726 Likes: 113 |
There was a very nice article on the Ern gun making family (father, mother, son) and their unique lock mechanism in Shooting Sportsman a few months ago.
Owen
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Joined: Mar 2012
Posts: 351 Likes: 6
Sidelock
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Sidelock
Joined: Mar 2012
Posts: 351 Likes: 6 |
Max and family are displayers at the SCI show and are a real delight to meet and visit with so if you have a chance to attend be sure to look them up!!
Sam Welch
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