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GUNS Magazine April 2010 - Page 22
GUNSMITHING • Hamilton S. Bowen • REFINISHING CAST AlUmINUm PARTS It’s tough, but a few shops do it well. ne of the most common problems in gunsmithing and custom O gunbuilding enterprises is refinishing aluminum well. It can be done well on a small scale but often takes more time and effort than the occasional job warrants so even professional gunsmiths may find it a good idea to vend out important pieces to finishing experts. Most of the trouble comes from aluminum castings (or rough castings of any stripe) which offer some unique finishing challenges that well-machined parts do not. The ubiquitous Ruger grip frames we handle daily at Bowen Classic Arms have been particularly troublesome and are the basis for the remarks following. durable and feasible to do in-house is a lengthy comedy of errors costing much time and treasure. After years of fussing around, we have hit on a couple of vendors offering finishes first-rate in every respect. But, first, the treatments that didn’t pass muster. Re-Anodizing Typically, hard-coat anodizing produces, thickens and toughens aluminum’s surface oxides. It does so by immersing an electrically charged part in It doesn’t seem like it now, but once these finishes are a four-star pain to apply a vessel containing sulphuric acid. Yeah! upon a time, aluminum was a scarce for gunsmiths out here in the trenches. The resulting finish is readily dyed or and desirable industrial material. The effort of Bowen Classic Arms Corp. stained an unlimited variety of colors Now it is pervasive in nearly every in finding aluminum finishes that are at from black to pink. A first-rate finish, field of manufacturing. It is light, the same time attractive, cost-effective, it toughens and protects the surface as formable, strong (in well as colors aluminum suitable applications) parts. The disadvantages are, and inexpensive. For however, considerable. all of these reasons, It is not easy to do in a the firearms industry simple shop environment. produces aluminum Outside vendors typically receivers, grip frames, have large minimum batch barrel shrouds, scope fees which makes doing the tubes and countless odd part or two very costly. other components. It is The biggest drawback is not, however, without the process does not seem its limitations. Just like to work well except on ordinary steel, aluminum aluminum parts of the “rusts,” forming an very highest quality. Our oxide coat in reaction primary use is on cast Ruger to the atmosphere. The single-action grip frames natural oxide that occurs AlthoughtheBlackTcoatingonthegripframe(above,left)isn’tanexactduplicate which often have voids and on aluminum does not oftheoriginalanodizing,itactuallystacksupprettywellagainstabluedsteelpart. inclusions of impurities. continue to develop as Nicelyfinishedandproperlyfittedaluminumpartsneednotbeaneyesore(below). The several anodizing rust does on steel but samples we have received rather stops at a certain from vendors over the years depth, leaving a nice, exhibited poor finish quality protective coating. Alas, because the pits would this coating is fragile and bleed out contaminants and wipes away easily. So, impurities wouldn’t always like steel, a protective color properly. surface treatment is Painting necessary to preserve Gunsmithing supply aluminum parts. This is houses sell a number of where it gets tricky. paints and dyes to color Aluminum is aluminum but most are variously finished with not terribly durable, even hard-coat anodizing, the baked paints. Further, paint, and a wide variety unless you are an auto body of exotic coatings. paint-and-fender expert Unfortunately, most of WWW.GUNSMAGAZINE.COM • APRIL 2010 22