doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com Cleaning before hot caustic blacking

I read something recently which confused me.
Had a couple of issues with scale or flash rust on a few parts that'd been in the tank so decided to do some homework, got to the bottom of the problem, it was me being a bonehead and not pre heating heavier parts when blacking in cold weather, but when reading through Brownells instructions after an Internet search for info , they said not to wash or degrease the parts in caustic soda/lye solutions. Now, it may be a shrewd move as they recommend using their cleaner and I'm sure it's a good product, but if the parts are blacked in a bath of the stuff, I couldn't see the harm it could do. I've always boiled parts clean in a separate bath with a pinch or two of caustic soda in the water, rinsed off then boiled in clean water before prep and polish. Having not experienced any problems other than the occasional bit of trapped oil or polishing compound creeping out from nooks and crannies in the hotter salt bath I wondered if anyone else has had any problems ?
I'm not Brownells bashing at all, Its homebrew salts in my tank so it may not apply but still curious what the reason is for not using it ? Perhaps it's not an issue with the hot tank . Maybe there's a light pickling agent in their cleaner that gets down into pits and kills any rust, some trapped remains of the caustic/lye cleaner may neutralise that and cause a blemish maybe ?
Any ideas Gentlemen ?

I have blued maybe 50 rifles using Brownells products. I follow the instructions to the letter.

Metal prep is the key. Absolutely no oil, grease, dirt, or anything on the metal. I matte blue, so I bead blast all parts first using fine potters glass beads.

1. Cleaning in the hot tank using the Brownells cleaner.

2. Cold water rinse.

3. Into the hot caustic tank at 285 degrees F.

4. Cold water rinse.

5. Into the neurtalizing bath.

6. Into the hot water tank, nothing else, pure distilled water.

7. Then into the water displacing oil tank for overnight.

Only problem I have had is using tap water: Our water source comes from a large reservoir (dammed creek) and it is treated with copper sulfate I think for algae control. The copper in the water makes gray colored spots on the final bluing finish, looks like the rifle has a case of the measles. Only cure is to start all over with metal prep.

So I started using distilled water. No problem since.

Considering the low cost of Brownells cleaner, it is cheap insurance.










I usually sand to 320 grit before bead blasting.






Next bluing project will be rust bluing. I have the solutions and have made some special holders for the barrel and action. Will be doing a rifle in the next two weeks.

That's a nice workshop set up you have there John.
I use de ionised water for the salt bath but normal tap water for washing, I was assured the tap water here is good enough but I still like to let it stand overnight to release any traces of chlorine before I use it.
I'd read that copper will kill the bath salts instantly but I'd imagine there's only a slight trace of it in your water, as you say though, distilled water works just fine.
Good luck with the rust blueing, it's good fun when it's working and we'll worth the extra time. A guy brought an old SxS I'd done a few years back for a check over last night, I swear the barrels looked better than when they were freshly done, maybe continued oiling and buffing over time adds to the look