I'm going to post this in both Gunsmithing and Muzzle Loading since muzzle loaders often want to re-create the authentic look and sometimes that was in a Brown or bronze finish and they may be aware of this process.
I was reading a book of formulas originally printed in 1907 and under steel bluing ran across an old formula for Bronzing steel. At first I thought it was the old Ordinance formula for cannon, but kept reading and it seems to be a modification of the Fume Bluing process except it turns the steel bronze colored and is supposedly permanent.
Basically it boils down to exposing the item to be bronzed to the concentrated fumes of a mixture of 50% Nitric acid and 50% Concentrated Hydrochloric Acid for a period of 3-5 minutes. (Concentrated was emphasized in the formula) Then the item is covered with a coat of petroleum Jelly (Vaseline) and heated until the petroleum jelly decomposes. The item to be bronzed must be perfectly clean with no residual oils and the bronze color is supposedly permanently embedded or becomes part of the steel. This appears to be almost a cold bronzing process, except for heating the Vaseline.
OK, so there are commercial products out there that will do approximately the same thing, but all of them I've seen end up with a deep brown-red (Plum) Bronze and require temperatures in the 600 degree plus range. Where this got even more interesting is that by the addition of Acetic acid to the above mix, by varying the proportions of the acetic acid percentages in the mix, colors from a Yellow bronze through the before mentioned brown-red, with no acetic acid, can be obtained from the fumes. Apparently the color variations are extremely variable. This process may explain some of the old, old shotguns I've seen in England, with yellowish bronze colored steel sidewalls on the receiver.
Is anyone familiar with this process and has possibly tried it? Any thoughts on the process? Am I barking at a fake fireplug? If no one has tried it, or is familiar with it, when I get moved back to Washington (or maybe Idaho) next spring I'm going to try it on some junked steel rifle parts just to see what happens. Would try it here, but most of my shop is either packed up or sold and the fume hood went fast. I am down to basic hand tools, almost.
Packrat
I was reading a book of formulas originally printed in 1907 and under steel bluing ran across an old formula for Bronzing steel. At first I thought it was the old Ordinance formula for cannon, but kept reading and it seems to be a modification of the Fume Bluing process except it turns the steel bronze colored and is supposedly permanent.
Basically it boils down to exposing the item to be bronzed to the concentrated fumes of a mixture of 50% Nitric acid and 50% Concentrated Hydrochloric Acid for a period of 3-5 minutes. (Concentrated was emphasized in the formula) Then the item is covered with a coat of petroleum Jelly (Vaseline) and heated until the petroleum jelly decomposes. The item to be bronzed must be perfectly clean with no residual oils and the bronze color is supposedly permanently embedded or becomes part of the steel. This appears to be almost a cold bronzing process, except for heating the Vaseline.
OK, so there are commercial products out there that will do approximately the same thing, but all of them I've seen end up with a deep brown-red (Plum) Bronze and require temperatures in the 600 degree plus range. Where this got even more interesting is that by the addition of Acetic acid to the above mix, by varying the proportions of the acetic acid percentages in the mix, colors from a Yellow bronze through the before mentioned brown-red, with no acetic acid, can be obtained from the fumes. Apparently the color variations are extremely variable. This process may explain some of the old, old shotguns I've seen in England, with yellowish bronze colored steel sidewalls on the receiver.
Is anyone familiar with this process and has possibly tried it? Any thoughts on the process? Am I barking at a fake fireplug? If no one has tried it, or is familiar with it, when I get moved back to Washington (or maybe Idaho) next spring I'm going to try it on some junked steel rifle parts just to see what happens. Would try it here, but most of my shop is either packed up or sold and the fume hood went fast. I am down to basic hand tools, almost.
Packrat
