doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com Copper hue under bluing

Working on some twist, and getting to the rust conversion stages, and there is a copper (rust) colored tint at the breech end. Not had this happen before. Assuming I didn�t card well enough on a prior step, but wondered if others have experienced this and what others have done to deal with it. I would prefer not to start over if I can help it. Thanks.

In the past I had a set of barrels that had a similar thing happen. It turned out that I had used a brass brush while cleaning them up.
The brass somehow transferred to the barrels and did not show up until the rusting process.
I was wondering if you might have done the same thing.

Thanks. No brass brush was involved. I must have missed something when carding. Haven�t found any other explanation.

Many slow rust bluing solutions contain copper sulphate which can plate out a thin wash of copper under some conditions. Laurel Mountain is one of the commercial solutions that contain copper sulphate, as do many of the recipes found in Angier's book.

This problem of copper plating out during rusting seems to happen more if the barrels are very warm during application of the rusting solution. I've also had a very thin wash of copper plate out on steel when acid pickling in hydrochloric acid that got contaminated with copper.

I use Laurel Mtn a lot and as Keith points out if the bbls are warm,,then the copper from the coppersulfate kn the soln 'plates out' for lack of a better term.
Other commercial solns use coppersulfate too I imagine, many of the home brews called for it.

You will also get the same plating w/the L/M if when applying you rub a spot back and forth to apply the soln even ever so gently.
This appears even if the bbls are cold and is a separate occurance from the above warm surface thing.

Once over and that's it. Go slow enough to make sure you cover everything the first pass. Don't worry if there's a small area not covered or one pass slightly misses the one next to it.
It'll cover up in the next cycle.

Scotchbrite any copper plated areas down to bare metal and blend the polish to the original. No need to remove all the rest of the bluing if it looks OK.
Re-coat and keep going. The repaired area will catch up in color within a couple coats.
Throw that piece of Scotchbrite you used to polish that damaged area away. You don't want to use it somewhere and drag copper back onto the surface again.

Thank you keith and Kutter.

Heat was not factor, but I may have been less careful about my passes. Glad I don't have to completely start over.