doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Copper color during rust bluing??

Hi All,

I wanted a glossier finish on my latest rust bluing project so I chose to use the C17 swiss black formula from Angiers book because it contains no acids.

After applying the first coat, the part turned a bright copper color and didnt want to rust. Its not a dull, fuzzy rusty copper, its a bright, shiny copper.

Im sure I made the solution correctly and the degreasing was sufficient.

Has anyone had this happen?

Thanks,
Jon

Without digging out my book & looking it up don't know what formula C17 is. Does it have a high percentage of copper sulfate?. Copper sulfate in solution can give a "Flash Plate" to steel. As I recall even though Angier gave a lot of formulas which included it he was not really fond of copper sulfate on this account.
I have been told that many machine shops used to have a copper sulfate tank where parts to be laid out were dipped in, giving a thin copper plate that would show the marks. By the time I started the trade in the mid 1960's layout ink (Dykem) was being used almost exclusively.

Question? Were your tanks brazed by any chance?

Are you using stainless steel tanks?

Mike

I'd guess a copper sulfate content w/o looking it up.

Laurel Mtn. will do that on occasion when you're laying on a first coat.
...A flash of copper on the steel in an area and no rusting because of it.

I've noticed it happens when the steel is warm. Or I needlessly go back over a spot that I've already covered and try to recoat it getting every little streak covered.


All this on the first coating on bare steel. Doesn't seem to occur or at least it doesn't effect anything (can't see it) after the blue has begun to build after a cycle or two.
Cool basement temps seem to work best for me when applying the stuff to avoid the copper plated look.


..Maybe the formula given in the book is incorrect. The amt of copper sulfate if it is in fact included may be too high. Just a guess there of course.

Hi Jonblue. I take it that you are using �Beutel� formula page 88. I have never had the amount of surface copper plate as you describe though I have had the odd tiny patch now and again. This formula calls for 1.2 grams of Copper Sulphate, 3 grams Ferrous Sulphate, 3 grams Ferric Chloride and 5 grams of Alcohol all in 100cc or � US pint water. Somehow I think you may have made an error in the quantity of copper sulphate in the mix so I do recommend that you re-make the formula. Also apply the formula very sparingly just enough to make the surface damp and try not to overlap passes if you can, I can not say much about the ambient temperature because it is always cool over here.

Yes, I am using the Beutel formula on page 88, and it has 1.2 grams of copper sulfate and 3.0 grams of ferrous sulfate.

Damascus, I greatly appreciate your suggestion, but Im a measure twice, mix once kind of guy. Im certain I made the solution correctly.

I applied it when the surface is warm, which is my practice so it drys quickly.

If this is because of the copper sulfate, why is it so frequently used in bluing solutions? What does the copper sulfate do?

No, my tanks are not brazed, it is stainless.

Jon

I can't comment on the temperature issue, I always apply the solution to cool metal as I find it easier to get an even coating if it isn't drying too quickly but everyone to their own..!
I have only once had a serious problem with copper plating from rusting solutions and indeed that was a copper sulphate based solution used on items of gun furniture when I was experimenting with alternatives to hot caustic blacking. It was so bad I had to resort to chemical methods of stripping it off where there was engraving.
Since then I have often used it on both steel and damascus barrels with no serious problems. One often gets a thin copper wash on the surface but it still rusts just fine and rubs off with the carding.
I agree with others' comments: don't re-coat, work on cool surfaces and be patient while it dries. If all fails use a non copper solution on this particular set of tubes. It may work fine on others. Remember, this is a 'black art'!

I don't have any idea why copper sulfate is in many of the old formulas. Maybe in conjunction with some of the other chemicals it helps promote the rusting. I don't believe that in itself it does that to the steel.
I've read that some of the old formulas have un-necessary chemicals in them or one that will cancel out another. With the long list that is in some I can believe it, but again ,,not a chemistry major here.

I did read somewhere ( a John Bivins M/L article I believe) that the developer of Laurel Mtn Soln, Rick Schreiber (sp?), put a small amt of copper sulfate in the L/Mtn originally as a marker of sorts.
As the coating quickly dries, especially on the first couple of coats on fresh steel, the dark blue/gray color is easy to see where you've been,,or not.
Personally, I could do w/o it being in there if that's all it's for. Every once in a while I still get a small copper plated area from over lapping a few strokes of the swab. Otherwise it's Ferric Chloride as the rusting agent AFAIK and that makes a first rate slow rust solution.

If the bbls are too warm,,it will 'plate out' in bright copper onto the steel.
Much the same way as any of the old mercury (bichloride) rust blue compounds will plate out the bright mercury but only onto brass, copper, gold, ect inlays in the warm steel for you.

Very stubborn stuff to remove, the mercury is. All your gold inlay work will look nickle plated if you use the wrong soln.
Shouldn't be any reason for using that merc stuff anymore anyway..

Does anybody have an idea as to what the copper sulfate actually does?

If I want to use a different solution, can anybody suggest what to do if it calls for mercuric chloride? I wont use it, period.

Should I simply omit it as long as there is some other oxidizer in the mix or is there a good substitute? I.e. Ammonium chloride?

Thanks for all the help guys!

Jon

Ammonium chloride works well just by itself. You can probably find it in that book under the old common name of SalAmmoniac.
It was and to some still is a good soft solder flux.
You can buy it in a solid bar form about the size of a bar of soap at a welding type shop usually.

Just shave off some pieces (it's fairly soft) and let it disolve in plain (distilled) water which it does very easily.
Use that as the 'rusting solution'.

No worrys about copper or mercury. It was a primary slow rust brown soln for many years. Can be very aggressive in high humidity and temps. You have to experiment with the soln % but just about any amt will get you rusting,,just more and quicker as the concentration increases.

Wrap the remaining bar of sal ammoniac back up tightly and store in a plastic container or bag. The fumes from the stuff will rust steel objects that are around it in the shop.

Can't get much simpler than that.