Technical Information for Gunsmiths and for Classic Car Enthusiasts

Gunsmithing Information

Firearms Finishes

by Les Bengtson

There are two basic types of firearms finishes. Those that cause a change in the color of the surface metal of a firearm and those that are applied to the surface but do not change the basic nature of the surface material. The first group of finishes consists of what is referred to as "bluing or browning" while the latter category comprises the majority of other finishes available. The purpose of this monograph is to briefly discuss the nature of bluing, the most common firearm finish, and then to discuss the applied finishes.

Bluing (or browning) is, most commonly, a modified form of rusting created under strictly controlled conditions to produce a cosmetically pleasing finish on steel. In industrial applications, it is referred to as black oxide. In the older methods, a solution was wiped on the clean part and then the part was allowed to develop a fine rust. This rust was carded off and the part wiped again with the solution. This process continued until the desired color was produced. The process is still sometimes used today on higher quality firearms and those, such as double barreled shotguns, which would be damaged by the more aggressive modern methods. The process is known today as the cold rust method.

The more modern method of bluing is to use a bath of caustic chemicals heated to about 285 degrees F. The parts to be blued are chemically cleaned and then immersed in the bluing bath for about 1/2 hour until they reach the desired color. In both types of bluing, the surface of the metal is chemically changed and the finish is in the metal.

As a side note, there is another form of coloring, not commonly encountered today, called heat bluing. This is the controlled heating of the part watching as it changes colors. The part is quenched in oil when the proper color is obtained. This was the process used to color certain parts of the Parabellum or Luger pistol.

The second major form of firearms finish is the class known as applied finishes. These finishes are applied to the surface of the metal and do not change the basic nature of the surface metal. By their nature, they are far more rust resistant than bluing. They also tend to be more expensive which is why they are not more common. These applied finishes range from common paint to plated finishes.

The British used a painted finish on a number of their service arms. The paint was easier to apply than bluing, provided greater rust resistance and was less expensive. It also had the property, in the proper color, of being less likely to reflect light- a prime consideration on both the battle field and hunting field. The painted finishes were relatively easily damaged, but could be easily touched up with a small bottle of paint. American ski troops often used white painted weapons. With the proper paint, this is still an acceptable finish for inexpensive firearms.

Plating is another form of applied finish. It comes in two forms-electro plating and electroless plating. Electro plating is applied by passing an electrical current through a part suspended in a plating solution. Hard chrome is applied this way and produces a very hard finish as its name implies. It produces a white-silver finish and may be either shiny or matte. Nickel may be applied by the electrical method. In this case, the part is plated with copper first and then the nickel is plated to the copper. Both processes produce a very rust resistant finish with good wear characteristics. Both will, however, eventually wear through and can let rust get under the surface.

Electroless nickel plating can be applied to both carbon steel and aluminum. It is available in either a shiny or a matte finish. Like the hard chrome it is very rust resistant and long wearing. Also like hard chrome it can allow rust to get into the part and pit it. I have a Colt Commander slide that was electroless nickeled which shows a great deal of minor pitting where it rests against the body in a Summer Special holster. After a number of years of concealed wear, the area above the thumb safety had turned black. When the finish was stripped, numerous small pits were discovered. All of your plated finishes offer much greater rust resistance and much better wear characteristics than bluing, but even with the best of care, they will wear off and let rust get started. Just as with bluing, they must be periodically refinished for maximum protection. This is one area where they are inferior to bluing. Bluing my be stripped off and a new finish applied with relative ease. Plated finishes must be removed by special stripping processes, preferably by the original plater. Since there are several plating processes available, each a little bit different, they often require a special stripping process only available from someone using that particular process. While there are some processes available that claim to strip almost any plated finish, they must be used with the utmost care. I have seen several pistols damaged by their use.

There is another form of applied finish. This is applied by hand by either dipping or spraying and offers the dark color of bluing along with the greater rust resistance of the plated finishes. Its wear characteristics are better than bluing but not as good as plating. Teflon finishes and our TAF-1 finish are examples of this type. We feel that the TAF-1 is superior in wear to Teflon and that is why we offer it. Both the TAF-1 and Teflon finishes are available in a low luster black which looks very well on a firearm. They can also be stripped by normal abrasive blasting which means they do not require the special preparation that a plated finish does when they must be refinished. Another benefit of the TAF-1 finish is that it may be applied to both aluminum and stainless steel as well as the more common carbon steel. This allows these two metals the protection of an applied finish for use under adverse conditions. I once rusted several parts of a stainless steel pistol while carrying it concealed over a period of a week in our hot Arizona summer. Applying a TAF-1 finish not only made the pistol less conspicuous, but it also prevented any recurrence of the rusting problem.

As can be seen from the foregoing synopsis, the choice of finish for a pistol is more complex than some would have us believe. Bluing is an excellent first finish for a pistol. It is relatively inexpensive, holds up relatively well except under harsh operational use and does not change any of the parts tolerances. It is a very good choice to use while you are setting up your pistol and getting all of the work done on it you want. If you decide you want something changed (different sights, trigger or mainspring housing for example) it is not a major problem. With a plated slide, for example, the plating must be stripped before most sights could be mounted and then the slide re-plated. After you have your pistol set up exactly as you want it, it is time to consider a better finish.

The plated finishes will change dimensional tolerances. Parts that functioned perfectly before may cause problems after the plating. This is particularly true with tightly fitted parts such as match barrel bushings, beavertail grip safeties and tightened slides. Trigger pull characteristics (weight of pull and crispness of pull) may be affected. This is the main reason we do not offer plated finishes. Additionally, after a number of years of experience with these finishes, we have found no one who can consistently turn out a top quality finish. This requires some pistols to be returned to the plater to be finished again, delaying the return of the pistol to the client.

After much experimentation, we have adopted the TAF-1 finish as our most rust resistant finish. It will wear, but still provides greater wear resistance than bluing. If you holster is cleaned periodically with a clean tooth brush and then blown out with compressed air, the finish will suffer less abrasion. This holds true with all types of finish. The ability of TAF-1 to be applied to all types of metal allows us to offer a dark finish for stainless steel and aluminum. In the areas where wear occurs, it can be touched up with cold blue (for carbon steel) or with flat black model paint (any surface) to reduce glare. Since these areas are worn away through abrasive action, all finishes will eventually show this wear, but only TAF-1 and bluing may be touched up in this manner. Most importantly, we do not find the build up of the TAF-1 finish to cause the dimensional problems that we have found with the plated finishes, making it easier to set the pistol up properly and then apply the finish without having to worry about how plating will affect the final fit of the parts. If there is a problem, it is easily solved and the pistol refinished without having to ship it back to the plater.

If you have any questions concerning the refinishing of your firearm, please feel free to contact us.

This monograph may be reproduced only for non-commercial use without other permission of the author. Reproduction for commercial use only by written permission.

Copyright © 1999 by Les Bengtson