There have been numerous requests on the MLML for information about barrel browning, so this explanation of how I do it is an attempt to share what I have learned about it over the course of 15 or 20 barrels.

The traditional method of browning is by rusting the barrel in some fashion. This was accomplished in a number of ways in the good old days starting with the easiest method of leaving the barrel somewhere damp to rust and probably more often using some corrosive chemical mixture to accelerate this process. I have tried using oxidizers which are readily available such as black powder dissolved in water and the washings from the barrel but these seem to be very slow and do not seem to rust very uniformly. The mixture I use comes from one of two listed in Foxfire 5. Both mixtures appear to be very similar and I am not sure which I used 16 years ago when I made up about 1 quart of it. The formula is approximately;

1 oz muriate tincture of steel (ferrous chloride )
1 oz spirits of wine (any of the alcohols; I use isopropyl)
1/4 oz muriate of mercury (mercuric chloride)
1/4 oz strong nitric acid (concentrated nitric acid)
1/8 oz blue stone (copper sulphate)
1 qt. Water

At this point a warning and an explanation; mercuric chloride obviously contains mercury and copper sulphate and ferrous chloride probably aren't good for you either. Use good rubber gloves when handling this stuff. Secondly, always ADD ACID TO WATER . In operation I think that the nitric acid and the metallic salts do the rusting and the alcohol is there primarily to break the surface tension of the liquid so that it spreads out more evenly. I have recently noticed that the alcohol seems to reduce or prevent the copper sulphate from temporarily copper plating the barrel.

I prepare my barrels by draw filing them smooth, using cutting oil to reduce pinning of the file and its accompanying scratches in the barrel. Chalk I am sure would do just as well. For octagon barrels, rapid cutting maintains sharp edges to the barrel flats. I follow this by sanding the barrel with fairly coarse abrasive paper (about 150 grit) with a fabric backing and wrapped around a flat surface for a sanding block. This block is to try to preserve sharp edges. Again I use cutting oil on the abrasive paper. When the barrel is smooth to my satisfaction, I wash it with either a strong solution of lye (sodium hydroxide) or caustic potash (potassium hydroxide), which ever is handy. Obviously wear rubber gloves for skin protection and use some form of eye protection. When making up the solution ADD CAUSTIC TO WATER never the reverse.

From this point forward I handle the barrel with rubber gloves only to prevent getting any grease on the metal. I support the barrel on two triangular pieces of kindling with the upper sharp edge touching the bottom barrel flat. This minimizes marks on the barrel during the browning process. I wipe the solution on the barrel with a small piece of cloth and leave it for several hours by which time it is usually dry. The copper sulphate usually darkens the barrel almost right away, but ignore that. I moisten the barrel with water sprayed on it from a Windex-type bottle and using the same piece of cloth from the original application, I wipe the moisture uniformly over the whole barrel and return it to sitting on the wood blocks. I repeat this every few hours as time permits. About twice every 24 hours, I card the barrel by rubbing it down with steel wool (preferably fine wool) using lots of water. The purpose of carding is to keep the rust building up as a smooth layer rather than a rough pitted surface. After carding, I rinse the barrel and give it a fresh coat of rusting solution and repeat wetting it every few hours if possible.

This process ends when the barrel is as dark as your taste prefers. For me this is usually 2 - 3 days. You end it with a very light wet carding and a good washing followed by a good oiling. Be advised that if you wash the barrel in hot or boiling water, the rust will turn a blackish brown and those barrels for which I wish a blackish colour, I wash at each carding with hot water (around 120 degrees F) in the laundry tub. While washing with hot water, I have had no trouble with the rusting continuing after I have finished the job. This after rust can be a problem if you use rusting solution to wet the barrel every few hours. The solution is to keep an eye on the barrel and continue carding it until the rusting stops. Ideally wash the barrel well in addition.

I used to card the barrel dry, but I feel that this method removes too much rust and is very difficult to control especially if coarse steel wool is used. I used to finish a dry carding job using a cloth and cut polish very lightly for the last carding and even after washing I sometimes had trouble with the solution continuing to rust for several days.

For those of you interested in bringing out the pattern in Damascus barrels or wrought iron originals, there are two excellent articles by Oscar Gaddy in the Double Gun Journal, volume 8 (1997) issue 2 and issue 3. I recommend them very highly. The solution he uses is very similar to the one from Foxfire 5 less the copper sulphate and which he states is called C - 26 (Birmingham Brown for twist barrels). It comes I believe from the book Firearm Bluing and Browning, R. H. Angier, 1936. His version is;

50 grams mercuric chloride
40 ml ferric chloride solution
9 ml conc. nitric acid
24 millilitres of alcohol
1 litre of deionized water

He develops the pattern by rusting everything, then carding, which leaves the higher carbon portions brighter (less rusty) than the low carbon areas and then using a ferric chloride solution to differentially etch these bright areas. This process takes a series of rustings, carding and etchings and if my attempts are any indication, is a lot easier said than done well. I would suggest that his articles are mandatory reading for anyone contemplating this process and I might as well give a plug for the Double Gun Journal in general as being excellent plus for its articles although most do not feature muzzle loaders. I have used my own preparation of the above solution and used Oscar's method on several barrels and barrel fragments recently and would offer the following observations; the solution eliminates the problem of copper plating the bright portions of the barrel during the rusting process, the more elaborate the damascus pattern the more difficult it is to develop the pattern and that the ferric chloride etching solution is essential to getting a sharp contrast in the pattern (I leave the barrels in for about 5 minutes or more). With regard to pattern I have found that the simple diagonal line patterns will "jump out at you" and be quite attractive and well defined by 2 days of rusting while the really tight figure 8 patterns and the tiny rosettes will take 4 days to 1 week of rusting and carding and even then may not develop to your satisfaction.

I hope my ramblings above are of use to some of you, the method has worked well for me.

Cheers, Doug Miller

Copyright & copy; 1999 Douglas C. Miller