I seldom do fume bluing anymore, only when the stray double comes in.  I prefer fume bluing over typical rust bluing for doubles because it will get into all the nooks and crannies and will generally not pool in crevices like wipe on rust blues. 

Fume bluing is fairly simple; if I remember correctly its 3 parts reagent grade Nitric Acid to 2 parts reagent grade Hydrochloric Acid (and by parts I’m talking drops in most cases), put into acid proof container. 

Plug the bore, oil free cleaned metal. Figure some way to suspend the parts, put parts & acid into a sealed box.  Mine is made out of Plexiglas.
   
Make sure that the interior temp is mid to high 90s, humidity about 60-70%.  Too much humidity and the parts will get water drops on them…which will cause irregular pitting.
   
3-4 hours, take out, card, boil, return to box, and let rust more until you have a decent finish. 

Couple of suggestions: 
Anything that you put in the box will be attacked by acid fumes, so make sure they are corrosive resistant i.e..Stainless steel, glass, plastic.  For example, I first started using a light bulb in the box to keep the temp constant, the acid corroded the bulb to the fixture, and ate thru the copper wiring inside the fixture.  I now use a heat lamp outside the box, and a glass thermometer inside the box to tell me when to turn the light off and on. 

A damp sponge inside the box will provide a fairly constant humidity. A bowl of water is too much, as the water will condense on the metal parts closest to the bowl. 

If you open the box and quickly remove the parts, there is no need to recharge the acid mixture.  The fumes are generally heavier than air, and will stay in the box. 


Have Fun 

Mike Hunter

Walt,
I used to do fume blueing way back in the 70's when customsing .45 Colt automatics for PPS.

Some three years ago I suggested this method of blueing to my Internet buddy Al Sledge in Southern California. He built a plexiglass cabinet and experimented with the method I had suggested. He quickly found that it produced excellent results. You can blue a rifle over a weekend, or you can do one fuming, boiling and carding per day and simply place a large sheet on paper over the parts when you are not working on them. This stops insects and other little critters walking over the parts and leaving marks on them which may show up on the next acid fume pass. 

One great advantage is that it will cover welding that may have been done in restoration, it may take an extra coat or two but it works, you can't tell where the weld was.

He sent me the results and his methodology when he had finished. This runs to three A4 pages in a word document and is far too large to post here.

If you send me an email I will know who to send this document too. My Email Address is:- 

harryeales@talktalk.net

People who have seen his original Winchester Hi-Wall that he re-blued using this method have all commented on the finish. It's the only method he uses now when blueing. I'll include pics when I reply.

Harry

Harry, I thank you and will email you shortly!

Walt

Harry,

     With all that text and some pictures as well, that sounds like a great DIY article for the Single Shot Rifle Journal!  Why not contact editor John (40Rod) Merz and ask him if he is interested?  I'd love to see it available to the entire group (as well as myself  )

Froggie

I found this article on a gunsmithing sight. It's by an old local gunsmith with a personality much like Bo Clarke. I haven't used it but I was hoping to someday. I would like to Brown my Borchart.

Mike and Harry, what do you think of his process?

Frank

THIS METHOD OF RUST BLUEING IS EASY, AND NOT COMPLICATED AT ALL. POLISH BARREL OR PARTS, AND THEN CLEAN WITH ACETONE, KEEP HAND OFF, WHEN DOING BARREL SWAB A GREASED PATCH DOWN IT AND THEN PLUG BOTH ENDS BY DRIVING IN WOOD PLUGS. NOW HANG THE BARREL IN A SMALL CONFINED SPACE, OR MAKE A GARBAGE BAG TENT OVER IT ETC. BUY A JUG OF NITRIC ACID AT YOUR LOCAL PAINT STORE, KIND USED TO CLEAN CONCRETE, POUR A OUNCE IN JAR AND PUT IT IN WITH PART TO BE BLUED ( DO NOT DO THIS IN YOUR SHOP).IN A FEW HOURS THE PARTS, AFTER THE ACID HAS ATTACKED IT, WILL TAKE ON A DULL FINISH. NOW KEEPING YOUR GREASY MITS OFF THE PARTS, HANG LIKE IN GARAGE OR UNDER THE EVES OF SHOP AND LET IT RUST. THIS WILL TAKE 3 OR 4 DAYS HERE IN OREGON, MAYBE LESS ON COAST OR BACK EAST. WHEN THERE IS A GOOD DENSE COAT OF FINE RED RUST ON EVERYTHING, CARD OR BRUSH IT DOWN TO THE BLUE,WITH A FAIRLY STIFF MOTOR DRIVEN WIRE WHEEL. THIS BLUE IS REALLY TOUGH, AND ANY AMATEUR CAN DO IT. BUT USE A LITTLE COMMON SENSE WITH THE ACID, IF YOU LEAVE A JAR OPEN IN THE SHOP YOU WILL RUST ALL YOUR TOOLS ETC. IF YOU WANT TO BROWN A BARREL JUST STEEL WOOL DOWN THE RUST A LITTLE AND OIL.

TOM RICE
- MEDFORD, OR, USA

frnkeore wrote on Aug 18^th, 2010 at 8:56pm:


Hello Frank,

You should have received my Email by now, so I'll let you judge between the two processes as described. 

I would think the local temperature and humidity will have a bearing on the time it takes for the metal to rust. That will depend upon where precisely you live. California will certainly differ from Alaska. 

Everyone will, or should, experiment on some scrap metal first, before reblueing their favourite firearm. 

Harry

MartiniBelgian wrote on Aug 19^th, 2010 at 4:18am:


Hello Gert,

You have Email.

Harry