I've been doing quite a few barrels in the past year. I've been using the methodology from the many refinishing documents like Flannigan's and Gaddy's found on DocDrew's site, as well as many other's found in books like Angier's, as well as from my collection of Vintage gunsmithing books. It seems like I've hit all possible internet sources as well. There's some "holes" in the specific methodology described, this thread is designed to fill one of them in, it's specifically about solution strength and it's effect on pattern throughout the rusting and etching cycles. All this directly relates to boiled black/silver barrels.
One of the points throughout the listed methodology is the need to start out with strong rusting solutions, and to use progressively weaker solutions as the cycles progress. There is no real specifics in regard to this, so I'm going to describe what I've found.
Initially, I used to plan for a minimum of six cycles for Twist barrels, and nine to twelve for Damascus. For all barrels I used an initial etch before rusting to bring out the pattern. For Damascus I would rust full strength for three cycles and etch, then then drop solution strength by half for the fourth through sixth cycles and follow the same 50% strength decrease for each additional three rust/etch cycles. I now realize that this concept is not optimum. What would usually result is that the barrels would develop very nice color, but the bluing was fairly dark with only limited pattern visible. I would then rely on the last etch to bring out the pattern and contrast. Often, it would result in a degradation of pattern, with patchy, streaky and unacceptable results. I knew Flanigan was achieving nice contrast early in the process, so I started varying methodology. This is what I've found, resulting in the filling of the methodology hole.
I found it is important to drop the solution strength in half with each of the initial rusting cycles. I now use only one rust with 100%, 50%, and 25%. I then etch. I use a fairly weak Ferric Chloride etch, about 3%. Usually for one minute. This brings out the pattern well and sets it up for additional cycles, all at 12.5%, or one-eighth strength. It's also easier to do an additional etch if necessary, since the etch strength is fairly weak. You can't use weaker rusting solutions initially, as they create blotches. Once you're to the 1/8th strength, the rusting is actually visibly different on the iron vs. steel layers, and the contrast actually improves with each cycle. Additional short etches with the weak acid nicely brings out more contrast, avoiding the degradation of pattern and the resulting streaks and blotches.
Regards
Ken
Last edited by Ken61; 04/14/15 07:34 PM.
