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Posted By: hereford Hot bluing hardware - 08/14/20 01:30 AM
Looking at setting up a small hot caustic bluing setup for screws, trigger guards, firearms, etc. Does anyone use an electric deep fryer for this? I just need something small and dont really want a propane setup forjust small stuff. Never hot blued before and was going to use a recipe that Damascus posted about a Birmingham blue.
Posted By: Craigster Re: Hot bluing hardware - 08/14/20 07:04 PM
Did some small stuff hot bluing at one point in time, heat source was a hotplate. Not anymore, much prefer slow rust.
Posted By: hereford Re: Hot bluing hardware - 08/14/20 10:16 PM
I rust blue everything but am doing a few restorations that had parts originally hot blued so trying to get it factory correct.
Posted By: battle Re: Hot bluing hardware - 08/14/20 11:46 PM
Just build a short pipe burner with propane.
Posted By: mark Re: Hot bluing hardware - 08/15/20 02:30 PM
herford, I was deep frying some fish in my 3 qt Cabelas fryer the other day and had the same thought. It is just the right size, thermostatically controlled and not too expensive. I worry about how the heat element , plated basket and SS tub would react to Blue salts.

Up until recently I have been using a SS salad bar tub on a propane stove with Unibath salts. It worked great but the last of my salts dyed and Unibath is no more so I am looking for a replacement.
Posted By: Der Ami Re: Hot bluing hardware - 08/15/20 06:44 PM
An old gunsmith friend ( now gone) tried stainless steel tanks and cautioned against it for the salt tank, saying it caused spotting. It is OK for the cleaning and oil tanks. Since he is no longer with us, I can't ask which series of stainless the tanks were made from.
Mike
Posted By: hereford Re: Hot bluing hardware - 08/15/20 06:52 PM
My concerns as well as I was afraid of using stainless steel. I would basically be suspending the parts so the plated basket wouldn't be used. Alot of the fryers I see have enamel coated tanks which makes me wonder because a YouTube video shows a guy bluing with one that appears to be enamel coated.
Posted By: Der Ami Re: Hot bluing hardware - 08/15/20 10:22 PM
hereford,
At one time I started making a small outfit to do small items like parts for guns that would have the barrels rust blued, pistols, etc. the same as you are asking about. I was planning to use a 50 cal. ammo can for the tanks and made a tray to fit inside from a heavy gauge iron wire screen. The plan was to use my 2 burner propane camp stove for heat and after cooling put the lid back on the ammo can for storage under the workbench. I never finished it and in the meantime I moved and am now too old. Be sure to let us know what you decide to use and how it works out. Don't wait too long like I did and wind up having to rust blue screws, pins and all the other small parts.
Mike
Posted By: Mike Hunter Re: Hot bluing hardware - 08/16/20 01:59 PM
I’ve been hot caustic bluing (hot salts bluing) for only about 25 years, so I’m no expert, but I’ll share a few things that I’ve learned. Hot salts bluing is one of my least favorite processes, it’s fairly easy once you get set up, but, it’s a real PITA overall. If I didn’t have to do it… I wouldn’t.

Most know that caustic bluing salts are basically lye (Sodium Hydroxide), pretty nasty stuff, which are superheated (280 deg+ well above the boiling point of water), in a super saturated solution meaning that you have to heat the water up for it to hold the amount of salts required.

Some thoughts:
Lye destroys most organic material: wood, leather, hair, skin, fats, oils, waxes etc.… which is why it’s such an effective drain cleaner.

Lye burns hurt, superheated lye burns hurt a bunch, and heal slowly, use the appropriate PPE and always keep a gallon jug of vinegar at the ready.

Keep aluminum away for the salts, the salts will quickly dissolve AL. Copper, Brass etc. will ruin the salts.

Bluing salts “creep”, they will creep out of your tank, and onto everything below it.

As for stainless steel, I’ve heard that it’s not recommended, but I have not had an issue. I bought my bluing set-up from a retiring gunsmith about 30 years ago, he had custom made SS tanks which I still use today. But keep in mind that there are over 20 different grades of SS, not all are created equal. I suspect that the majority of SS cookware: pots, pans, fryers etc. is now imported from overseas, no telling what the metallurgy is of that stuff. If I were making them today, I would look at 316.

Electric fryer, I wouldn’t recommend it: First, most heating elements are made up of Kanthal, Cupronickel, Nichrome… some contain copper and aluminum, most contain chromium. none you want in a super-heated lye bath. Secondly, the salts will creep into everything. Quickly destroying the electronics/ internals.
There’s a reason why the propane burner set-up is used in the majority of caustic bluing set-ups.

Hot salts bluing is temperature sensitive; you don’t control the temperature with heat (i.e. thermostat), you control the temperature by adjusting the solution.

We all remember 5th grade science class, pure water boils at 212 deg, no mater how much heat you apply you will never get pure H2O above 212 deg… it will be steam.

The super saturated lye solution needs to boil around 285 deg f, if it starts to boil too low, you ass more salts, too hot add more water… Which brings up another point, adding water to a super-heated solution, will cause the water to almost instantly turn to steam…. Lots of splatter…and not just water but super-heated lye. Wear protective clothing, and keep a gallon jug of vinegar handy.
Posted By: SKB Re: Hot bluing hardware - 08/16/20 02:46 PM
Originally Posted By: Mike Hunter
Hot salts bluing is one of my least favorite processes, it’s fairly easy once you get set up, but, it’s a real PITA overall. If I didn’t have to do it… I wouldn’t.


I concur completely.
Posted By: mark Re: Hot bluing hardware - 08/16/20 03:22 PM
Any one have knowledge or experience with this?
https://www.epi.com/black-oxide/steel/hot/ultra-blak-400/
Posted By: hereford Re: Hot bluing hardware - 08/16/20 03:23 PM
Thanks Mike. Good points. I'm a veterinarian and completely agree with the quality of stainless as there is definitely varying qualities when it comes to surgical and medical equipment. I'm about ready to purchase or build a small propane setup and find a German stainless surgical tray or tub and give it a run.
Posted By: Mike Hunter Re: Hot bluing hardware - 08/16/20 04:09 PM
Personally, I would just buy a tank from Brownells, they are made for the task, and last forever. Caustic soda will not rust steel
Posted By: mark Re: Hot bluing hardware - 08/16/20 04:58 PM
I have used a SS salad bar tub for over 10 yrs with Unibath salts and had good results. I can't speak to how it may work with other salts. I believe Brownell does not recommend SS tanks with there salts.
Posted By: Mike Hunter Re: Hot bluing hardware - 08/17/20 02:17 PM
Unibath?? they still in business?

As I stated above, not all Stainless steel is created equal. There's a whole bunch of "stainless steels, some resist the effects of caustic soda better than others. I know that Du-Lite sells 304 stainless for their bluing tanks.
Posted By: mark Re: Hot bluing hardware - 08/17/20 08:33 PM
Unibath went out of business awhile back. I just used up the last of my salts and am currently looking for a substitute.
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