doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com Rust Blueing Help

Hi everyone,
So I was wondering if anyone could help me on some rust blueing troubles.

Basically I�m struggling to get the deep jet black colour and currently only getting a light black/grey. I�ve read Angiers book and decided to try a few formulas out but with pretty much the same results. I�m getting no streaks or blotches, so happy with my degreasing and application of the solution but just the colour.

Ive tried C.17 swiss black (beutel), C.19 ferrobronze and C.10 Twist barrels K Birmingham black. The first rusting is a good coat of brown/red rust and takes 4ish hours in a sweat box of 40C and 80% humidity to form. I then boil for 15mins in distilled water to convert the rust and card off. This gives a light grey colour. The second rust coating takes a little longer and not as thick but you can see it�s there. I then repeat the process in boiling and carding and get a darker grey. The third coating then takes a good 18 hours plus to get a little bit of rust and after boiling hardly changes the colour. The forth coating barely puts any rust on the part at all, after 24hours in a sweat box. I believe this is where it�s going wrong in obtaining a real deep black and was wondering if anybody else has had these problems on the 4th application.

The only things I can think of are:

The test pieces I�m trying it on first, before my own William Powell shotgun barrels are walther rifle barrel off cuts and may be high in chrome and nickel making the solutions ineffective. However I know people in the UK can rust black walther barrels with amazing results so not sure about this one.

Or maybe im getting the boiling wrong, maybe too hot or for too long, causing the metal to reject the next application (trying 5 mins boiling time as I write this now)

Was also thinking of increasing the solution concentration by adding less water than what Angier quotes to see if this will get me better rust coats on the 3rd and 4th application.

Apart from that I�m out of ideas and any help from the more experienced rust blue �ers on this forum will be much appreciated.

At this point, I'd guess the issue is with the composition of your test barrel. I regularly use C.10 and C.19 for blacking, both yield good results. In fact, I usually begin diluting the solution after the third application or so, because the black is so deep it's harder to etch. (C.10 used on Damascus and Twist). Having problems with C.19 is also surprising, as IMHO it produces an exceptionally deep black on fluid steel barrels.

The only other thing I do differently than you is allow longer rusting times, with four to six hours of moist heat, followed with dry heat throughout the overnight. I use shorter periods much farther down the process, after the color has been established and I'm trying to maintain contrast. (Damascus and Twist).

I suspect, though I'm not certain, that an Aqua Regia mix (HCL and Nitric Acids, along with Iron) is reactive enough to color some rifle barrels. It's certainly unnecessary for Vintage shotgun tubes.

Regards
Ken

Hi ken

Thanks for the information. I�ll try an aqua regia solution on them and see how it progresses. I remember reading somewhere that this can slightly matt the steel so I avoided it cause I�m aiming for a high polish finish but now you recommend it I�ll have a go.

I�m also going to find an off cut of some shotgun tubes and try the ferrobronze mix on them as well. This should be more in-keeping with the barrels i eventually want to black. I guess I thought one mix should work on most steel but this clearly is not the case and you have to adapt to which barrels you want to black.

Thanks for your time and knowledge

JMH,
I'm not as experienced as others here, but something to think about is the polishing. Sometimes steel will not color properly if polished too highly, especially if hard. I have trouble with Mauser bolt shrouds highly polished , by hand. Re-polishing with 320 grit cloth corrected the problem. If you are polishing them with a "wheel", I suggest you try a sample polished by hand, with worn 320 cloth.
Mike

Try your soln just as it is along with your rusting temp, time and humidity,,but on a plain piece of hand polished cold rolled steel. I'll bet you get some nice results.
Your Wm Powell bbls won't be far off from that anyway in how they respond.
I suspect those Walther bbl cut offs are either stainless steel of some high corrosion resistant alloy from the way they are coming out w/a grey color and less rusted as you go along.
Maybe they need an etch coating first before the bluing soln will 'take'. Maybe they'd respond to an Express Blue better,,All sorts of little things happen that you end up sorting out over time. But when starting out and wishing to do plain older steel bbls,,you certainly don't need that stuff in your way.

Less boiling time hasn't ever been a plus in my experience. They do need some time in the tank to convert.
Leaving them in an extra long amt of time doesn't seem to gain anything though. I usually let a set boil for 10 to 15min then out it comes. It's as dark as it's going to get at that point.

Don't know about shotguns, but for rifles using one of the nitric acid, HCL mixes, limit the rusting period to no more than three hours.
Longer rusting will definitely etch the barrels. nice matte finish.
This is in a heat box at about 90�F with damp towels inside.
Chuck

Thanks for all the replies.

I�m polishing to 600 grit and smooth over with grey scotch brite to blend it all together. It gives a sort of burnished effect. Would this be an issue to get the first coat to bite I wonder? I�ll try a 320 finish as you suggest with no scotch brite.

I had a look on lothar walther website and they use a Chrome-molybdenum type steel coded LW19. I�m pretty sure my off cuts aren�t stainless steel as they are magnetic and accept the usual cold blue touch up paste which I use to check if the metals will most likely black. It�ll be nice to see if I can solve this problem with these off cuts but I think the steel is completely different to the ultimate goal of blacking the William Powel barrels so I�m going to source some new test pieces.

I know Johnsons barrel browners can rust blue the walther barrels with amazing results here in the UK so it must be possible but I guess they�ve had generations to perfect the art and do it for a living.

Well I�ve got a few more things to try now, might take some photos at the different stages, to upload here, and see if you guys can spot something obviously wrong.

JMH

My final polish is with the Gray 7448 PRO pad, so that's not the issue. I use the Maroon 7447 PRO pad before it. After the tubes have been polished to 320. (Damascus and Twist) It's the steel.

Cold Blue is nothing like the rust bluing process, it's a coating which typically includes Copper Sulphate.

600 grit is not unreasonable for Fluid Steel, 400 is considered the minimum for Field Grade tubes. For Damascus and Twist, you need a little texture for the solution to "Bite". You typically etch the tubes before your first rusting as well.

I agree with the previous posts that suggested the Walther sections were probably colored with a different type solution.

Regards
Ken

Ok I�m sorting some new test pieces out tomorrow and I�ll try ferrobronze on it.

Out of interest have you or anyone else tried Aa 22 Black brown solution. Angier rates it quite highly in his book and the ingredients are pretty easy to get. Maybe worth a try as well.

And one last thing, when I put the test piece in the boiling water it drops the temperature below the boiling point for about 15-20 seconds. It then climbs back and converts the rust, but would that initial drop in temperatures cause any detrimental effect on the metal colour? Just a thought.

JMH

Interesting. HCL and alcohol are very reactive, in my experience, the alcohol evaporates quickly, concentrating the effects of the HCL, making it very corrosive. HCL is extremely prone to after-rustng, no doubt why Angier noted that neutralization was necessary. Possibly this is mitigated somewhat by the Bismuth oxychloride, which is essentially an inert white pigment. But, my experience with it was on Damascus and Twist, with solutions containing alcohol creating a thicker coat that is harder to etch. It may be totally suitable for Fluid Steel. If you try it, please post the results.

A temp drop of short duration is no big deal. You can actually achieve the conversion simply by pouring boiling water over tubes in a non heated container, but it requires several changes of boiling water.

Honestly, IMO, you're chasing the wrong rabbit down the wrong hole, and I recommend you go back to the methodology of your first test, but using the appropriate steel samples. I predict you will be successful.

What type of tubes does your Powell have?