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Author Topic: DIY rifle bluing  (Read 275 times)

Offline Novagun

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DIY rifle bluing
« on: November 14, 2018, 02:50:04 PM »
There are several ways to put a hard wearing blue finish on steel gun parts, many involve using hot chemical baths. They use caustic and dangerous chemicals that also produce dangerous fumes and are not suitable for home use,
 These hot baths can also cause a process called hydrogen embrittlement in hardened steels: not a good
 thing for gun parts that can be under extreme pressure which could cause the brittle parts to fail.

 For home bluing I (Dvinme) use a very simple process of controlled rusting, which achieves the same result as a hot chemical bath. Bluing is in fact a durable form of rust, iron oxide. There are several steps that need to be repeated to blue the steel.
The process takes approximately one hour to complete, but can take longer if you want really dark bluing.

I want to emphasize that the quality of the final finish will depend very much on how well polished parts were to  begin with, Etching for about two minutes gives a nice non reflective finish that wears extremely
 well..
If bluing barrels both muzzle and breech need to be sealed to prevent bore rusting. I machine up two tight fitting soft wooden plugs and force them into muzzle and breech, leaving just enough wood protruding to be able to hang the barrel in a tank on wires.
 
ChEMICALS NEEDED:

 Plain salt          ( Not iodised table salt)
White vinegar
Hydrogen peroxide
Degreaser         (Acetone, white spirits)
Distilled water.  Tap water may be satisfactory but town water introduces chemicals such as fluoride or                                                 
                           Chlorine

EQUIPMENT NEEDED:

Rubber gloves.
Fine steel wool.
Safety glasses.
Suitable containers   (for mixing and soaking. Note. Steel containers should not be used for the etching                                    and the rusting process because the steel in the container, or the tin or zinc coating will react with the bluing agents affecting the result. Glass or plastic is fine for mixing the chemicals.

THE PROCESS:

White vinegar is used for etching the parts after degreasing, Salt and hydrogen peroxide make the bluing solution. Use rubber gloves during the whole process as the bluing solution is mildly acidic and gloves prevent leaving finger prints that show up later on the blued parts.

1. Degrease parts thoroughly
2. Soak parts in the white vinegar for two/ three minutes to etch the surface mildly to take the blue for a     satin finish. Less than a minute for a highly polished finish, Try a few test pieces to get the required finish.
3. Rinse off in clean cold water then dry with paper towel.
4. Mix up rusting solution. Two tea spoons of PLAIN salt to half a cup hydrogen peroxide,
5. Mix well and brush this solution onto the parts to be blued with either a clean cotton bud or fine brush covering all parts completely,
6. Immerse into ready boiling water for 4/5minutes, keep the water boiling.
7. Remove from water being careful not to damage any surfaces and dry with paper towel.
8. Lightly rub just the fine powered rust film off the surface,
9. Rinse with water then reapply the rusting solution.
10. Back into the boiling water for 4/5mins
11. Repeat the process at least 4/5 times until the blue colour is what you want. Repetition will darken the colour.
12. Rinse again with hot water and dry off.
13. While the parts are still hot immerse in oil for 4/5mins.
14. Remove from oil and wipe clean. The parts should now be perfectly blued and ready to assemble.

 Doesn’t seem to matter what oil is used but really thin engine oil seems to penetrate into the
 pores of the steel well and is lot easier to clean off than thicker oil. Use either glass or stainless steel
 containers for etching and rusting solutions. The rusting solution will very soon eat a steel container away
 and will contaminate the solution as well.
 A longer boiling container will be needed to do barrels and may have to be made up from scrap stainless steel.    I use just a two burner gas stove for all the boiling because it is long enough with the two burners going for barrels.
 If followed correctly this method produces excellent bluing as good as a factory rifle and better than
 many. It resists wear very well and lasts for long time.




Offline Akzle

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Re: DIY rifle bluing
« Reply #1 on: November 14, 2018, 09:58:23 PM »
couple things to add:
USED motor oil (all the modern detergents cooked out of it)
and the rust we shoot for in bluing, I believe, is iron ferrite or magnetite FeO3, not iron oxide (FeO)

powdered ferrite can be produced by elctrolysis (also good method for de-rusting old parts) and was called for in some fume bluing recipes.

Offline Dvlnme

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Re: DIY rifle bluing
« Reply #2 on: November 15, 2018, 08:42:33 AM »
got some terms wrong good to know you on to it and picked them up akzle,coz i missed them.
 cheers mike

Offline Akzle

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Re: DIY rifle bluing
« Reply #3 on: November 16, 2018, 08:46:03 AM »
Not at all Mike. It's still iron oxide, just with more of the oxide.
And the correct elements are actually Fe304, so I was close but wrong.

Here's a good thread discussing this very thing:

https://www.finishing.com/44/69.shtml

Offline Akzle

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Re: DIY rifle bluing
« Reply #4 on: December 08, 2018, 12:00:37 PM »
Hey dvinme, where are you getting your hydrogen peroxide? I stopped at the chemist today and they have a 6%w/v solution, diluted with some other crap (http://www.pharmacydirect.co.nz/Home-Essentials-Hydrogen-Peroxide-20vol-100ml.html looks like the stuff)

Offline Dvlnme

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Re: DIY rifle bluing
« Reply #5 on: December 08, 2018, 07:45:23 PM »
Was lucky got some peroxide from mates wife who is an industral chemist some years back but am just bout out myself now and she no longer working,good thing you reminded me coz got to get some more myself
 check out chemical suppliers on line thats what I will be doing,trouble is they only do quite large bulk
 quantitys usually,but may supply smaller amouts,often depends on who you talking to if they will do the small amounts we use.
 cheers mike