Hot Blueing of Guns
I have been to many "gun" sites and could not find a formula for "hot" gun blueing. I have found your recipe to be very interesting. Why couldn't I find it elsewhere?Eric P
- Philadelphia, Pennsylvania
Hi, Eric. I'm not sure, but possibly two reasons: first, many of our readers are professionals so they frequently reference and quote the metal finishing textbooks whereas your average gun enthusiast probably would not; second, hot bluing is a dangerous operation that should probably only be practiced in a proper industrial setting, not in the back room of a retail store. We have a Black Oxide vs. Gold Blackening FAQ that may help a bit. Best of luck.
You can try "gunsmith supplies" search and probably find instructions and bluing compounds. The modern bluing solutions are very good and it probably wouldn't be worth trying to make your own. As was said, hot bluing is not a back room project. The solution I use is a caustic soda solution heated to 300 deg. F. It will eat thru leather, wool, skin, etc., and will cause chemical and heat burns. The fumes will deteriorate any metal in the area, so a very good ventilation system is required. Personal protection is a high priority.
Good luck,Ed Kay
- St. Louis, Missouri
Hello, I have a pre war model-70 Winchester. I just had the floor plate, trigger guard & screws blued. however they are too dull to match the rest of the gun. can these parts be polished by me to bring out more luster to match the rest of the gun? thanks,Bruce M Hissom
retired - Star Junction, Pennsylvania
The bluing can be waxed or oiled to bring more luster, but I suspect what really needs to be done to to polish the bare metal and re-blue it.
Ted Mooney, P.E. RET
Brick, New Jersey
June 5, 2008
I have an old engineering book "Dictionary of Metals and Alloys" 1939, [find this book at Biblio.com ] which describes the HOT BLUEING process very well and safely and have used with good success.
Thoroughly clean the articles in ammonium sulphide, and hydrochloric acid for a "few" minutes" will lightly etch the surface and create a light rusted effect which will improve the depth and darkness of the finished result.
Coslettising bath of a heaped desert spoon of phosphate of iron to a litre of water which needs a few drops of phosphoric acid to dissolve into solution...boil the articles for 1/2 an hour or more...longer produces deeper penetration to a small extent...leave to dry overnight and oil.
Granodising is an electrolytic process using a solution of zinc phosphate acidified with phosphoric acid and passing a light current from the negative cathode (the article) to a carbon anode. Articles acquire a dense black coating which is highly resistant to oxidising...can be applied to zinc, cadmium, iron steel, stainless steels and copper/brasses etc
Carver - New Zealand
^-- this reader rates this thread:
December 11, 2009
I have have tried my hand at Hot Caustic Blueing. I have a couple of problems I need assistance with. I have several parts that did not blue. Several that did. One that looks like it has freckles on parts of it. I thought all parts were the same type of steel. They all draw to a magnet. My frame did not blue at all. My slide blued to a good color but has freckles at edges. They were in caustic bath at same time. Some of my small parts also blued and some didn't. They to were also in caustic bath at same time. Any Ideas? Thanks SkipSkip Kalmar
Hobbyist, maybe One day gun smith - Heath Ohio
December 2, 2010
Just came across your question. I know you posted it a year ago, but since it didn't look like you ever received a response, I thought I'd throw in my 2 cents.
Stainless used in guns is 400 series and magnetic. It will not blue in ordinary salts. There are salts available for stainless. Some alloys work and some don't.
It's always advisable to try to blue a matte finish vs a polished finish. Polishing stainless is almost always a guaranteed failure.
Speckles on edges are indicative of poor cleaning. When the part goes into the solution, if there is any floating oil, the part will pick them up and it acts like a mask and the salts won't penetrate it.
Hardened parts, castings, will leave a red to purple tint and again, the courser the finish, such as matte, will offer a greater chance of a darker blue.
Hope this helps!
Precision Bluing - Greene, New York, USA