The secret I found for working with Plum Brown is to suspend the barrel so its hang vertically. Then, start at the bottom, heating the barrel with a propane torch. What heat "Escapes" the immediate area, RISES' and begins heating the barrel above where you are working. I kept the torch working just ahead of where I was applying the plum brown. The Steel Browns Immediately! I got a very nice dark brown finish. As I worked up the barrel, of course, some of the acid washed down over the area I had already browned, leaving a yellowish residue. But, I worked the barrel, doing one flat at a time, and turning the barrel to do all 8 flats in one section- about 4-6 inches long , before going further up the barrel.
I let it cool, until I could hold it in my hands and make a visual inspection. I found a few places where there was bare metal between "Strokes". I reheated those sections of the barrel, and applied the acid, until the brown was blended evenly. Then I let the barrels cool again.
I washed the barrel off in tap water, scrubbing off the white/yellow residue. You do have to flush the entire working surface with alcohol to remove all oils, including the oils in your own fingerprints, before this process begins, or you get spots, or fingerprints on the finish. Likewise, after rinsing, if you see bare metal you missed, again, and have to heat the barrel up again, flush the barrel liberally with alcohol to remove your fingerprints, and handle the barrel with paper towels, or rubber gloves that are clean of grease and oils. I suspended my barrels from a coat hanger, hung over the rail for my garage door.I left the door up to give better ventilation for the fumes, and opened the door to the house up so that the warm air would come out of the house, and push the fumes out of the garage as they rose.
To Darken the Brown, I then heated the barrel up, this time sweeping my torch up and down the barrels to get them very hot, and then sprayed the barrels with WD40. The oil and the dryers in it burn, and creates fumes you don't want to breathe, so stay upwind of the barrels. The spray itself will indicate the direction of any wind currents for you to watch.
Burning the oil into the pores of the steel left a nice "Hershey-Chocolate" Brown barrel finish. Over the past 30 years, the finish has lightened a bit in UV light exposure, but its still a durable finish, and remains attractive. I get other shooters asking me about the finish every time I shoot the gun.
You can not get good results with this finish if you try to apply it to a cold steel barrel, or to even a Warm barrel. The barrel has to be hotter than the boiling temperature of water( 212 Degrees F.) to work at all.
I think the directions talk about 275 degrees, but you have to heat the barrel a lot hotter is you use a stove, as it begins to lose heat as soon as the barrel is removed from the heat. Its a race against time, and when the steel cools too much, you will have "patches".
You may want to have an "Assistant" to hold and sweep the torch on the barrel for you while you use both hands to deal with the brush, and barrel. I didn't have an assistant, but managed to deal with the barrel by walking around it as it hung from the garage door rail. There obviously is some planning that has to go into this kind of project, but you can do it.
Not everyone likes the color brown I achieved, nor is willing to do this kind of work that I describe. That is fair. Those who prefer the cold brown solutions, like Laurel Mountain Forge sells, use different techniques, and sped a few days to get the results.
When I did my work, I was impatient to get this kit gun completed, and into the field, so that I could get used to it for the upcoming hunting season. I was not my most "patient" self, I admit. The Hot Brown method, using B/C Plum Brown solution served my purpose.
The LMF products were not then available. I look forward to using them on a gun I want to Rust Blue.
