Choosing and Using Polishing Tools
A good polishing job can save a gun from the junk heap, but a bad job can send it there. Heres how the professional does it.
As a gunsmith you are probably involved with some type of metal refinishing. If not directly in your own shop, you may be dealing with a specialist who does it for you. Even though we deal with blueing on a day-to-day basis, sometimes its good to be reminded of the basics. Our concern here is with polishing itself, rather than the actual coloring of metal.
There are as many ways to ruin a firearm through improper polishing techniques as there are firearms to ruin. Potential problems include rounded corners, dished screw holes, wavy barrels, dings and gouges that are not polished out, blueing over rust, letters and numbers pulled, and bead- or sandblasting used in an attempt to cover poor polishing techniques. The results? The destruction of firearm value.
By using proper techniques, however, many common firearms, ready for the junk heap, can be reblued to like new condition after proper and careful polishing. Note that rare or valuable firearms should not be reblued, as their collector value may be higher in original and untouched condition. Such arms, if they are to be refinished, should be restored by restoration expertsand that process is beyond the scope of this article.
Of course, polishing a firearm for blueing takes a little more time than just using a wire brush on the barrel and then rubbing it on a loose muslin polishing wheel. It is more ignorance than laziness that prevents good polishing.
The purpose of polishing is to prepare the metal for whatever final finish is to be applied. Firearms can be blued, anodized, or even left white. No matter what material you are working withsteel, aluminum, brass, woodall exposed surfaces must be prepared in a manner pleasing to the owners eye. Some of these finishes will:
* Give the surface of the work the same homogeneous polish.
* Vary the finish to present a pleasing contrast of smooth to rough.
* Engrave or etch the surface in pleasing patterns.
* Contrast blue to white.
There are generally two accepted types of blueing in use today. Both give a blue-black or black finish to ferrous material, and both are mildly rust resistant.
Rust blueing is an actual rusting process which requires careful monitoring. It is slow, etches the work, will not attack solder, and is more rust resistant than the chemical hot blues. Rust blueing is very pleasing and is found on high-grade over/under or double guns. Hot chemical blues attack solder and chemically oxidize the surface. Hot chemical blueing is quick and easy, however, and is generally used on commercial production-grade guns. Browning is another controlled-rust process which ultimately produces a brown finish to ferrous materials. It too is mildly rust resistant.
Plating is the addition of another metal to the surface of the material by electrical means. The process can be used for rust resistance as well as to give hardness, lubrication, or any other property of the material which is being used for plating.
Exotic finishes such as Mag-N-Flux are very rust-resistant and can perform a variety of tasks in keeping guns in good condition. Anodizing is a method of coloring aluminum which actually dyes the metal. Other processes can react with and dissolve aluminum. All of these finishes require careful polishing of the base metal to give the desired final result, and any step which is neglected in leading up to the final finish is detrimental.
There are two basic metal preparation processeshand and machine. Hand finishing is done in a number of successive steps. It is the mark of the professional gun bluer and finisher. The steps involved are to:
1. Remove machine marks with files.
2. Remove file marks with abrasive cloth (80/120 grit).
3. Remove polishing marks made by previous polishing with successively finer grades of cloth until final finish is reached. (180-grit up through crocus cloth if desired.)
The polishing cloth should be used with a backer that has no sharp edges to scratch or gouge should it accidentally come in contact with the work. The backer must conform to the shape or radius of the work being polished. Cutting oil may be used to keep the cloth from clogging with polishing debris. It should be noted here that abrasive polishing stones may also be used. They are available in a variety of grits from fairly rough down to India Hard, which will produce a very shiny finish. As these stones are not flexible like cloth, they will help produce the ripple-free, waveless finish needed for an ultra-high polish. Stones may also help for getting into corners and crannies inaccessible to cloth.
Each successively finer grit of polishing paper must be used at a 45-degree angle from the previous. This will enable you to see when the previous polishing marks have been completely removed. (If all polishing is done in the same direction, it will be difficult or impossible to see when the removal of the marks of the previous grit is complete.) Some gunsmiths feel that the last and finest grit of polish should be done perpendicular to the longest flat surface being polished, and that polishing should follow the round surfaces. Thus, a barrel will have the final polishing applied in shoe-shine strokes, rather than strokes end to end (unless it is an octagonal barrel). The final luster found in the best hand polishes may be applied with Scotch-Brite, crocus cloth, jewelers rouge, or some other material of your choice. (Well have more to say about final finishes in a moment.)
Machine polishing has probably ruined more guns than it has saved. It is quicker than hand work, but much more care is required to do it correctly. Everyone seems to have a method of machine polishing that works best for them, and youll probably discover a technique that works best for you. Just remember that polishing wheels cut much more quickly than hand polishing, and can ruin your work before you realize what is happening.
There are several basic wheels used in machine polishing, and each has its detractors and proponents. Here are some of them:
* Hard Felt. Cuts very fast! Hard felt is good for flats when used in the same manner you would use a surface grinder. Excellent for polishing up to final finishes.
* Spiral Sewn Muslin. Does not cut as fast as felt. Best for general polishing, but will dish out holes, round over corners, and pull letters and numbers.
* Loose Muslin. Used for final polish. Cuts slowly, but will dish holes and pull letters and numbers rapidly. With rouge, the loose wheel will produce a mirror finish (provided the base polish has been done correctly).
* Wire Wheels. Used for removing loose surface rust, scale, and dirt. Wire wheels in various grades can be very useful in final finishing.
* Other Wheels. Air bladders, flappers, and machines such as the square-wheel grinder are available. These are sometimes useful for difficult surfaces and unusual applications.
The actual technique of machine polishing is much the same as hand polishing. First, file out any machining marks, then polish with successively finer grits until the desired polish is reached. Finally, use the same 45-degree process for removing all previous marks before moving on to the next finer grade of polish. Caution: Do not mix wheels and polish grit grades. Have one wheel for each grade of polish.
Here are some pointers gleaned from gunsmiths across the country:
* The work must be kept moving under the wheel; a scoop will be polished into the work if it is stopped under the wheel. A scoop will have to be removed by filing or hand polishing, because any attempt to get it out with a polishing wheel will only make it worse.
* When polishing flat surfaces, polish from the center of the flat toward the edge. This will allow the wheel to leave the work without rounding over the edge. This is especially necessary on octagonal barrels where additional care must be used to prevent waviness in the flats.
* Around screw holes, polish toward the edge, and rotate the work around the hole to prevent dishing.
* On round work, polish from the center toward the edge to prevent the wheel from rounding over any edges.
* Small wheels, or specially shaped bobs, are useful in getting into areas a large wheel cant, such as the flutes in cylinders. Make the bob smaller than the shape to be polished so it polishes half the area at a time. Reversing the work and polishing the other half allows the bob to polish toward the edges, helping to keep them from becoming rounded off.
* Always polish so the wheel leaves the worknever so the edge is introduced to the wheel first.
* Letters and numbers will be pulled if sewn or loose wheels are used. A hard wheel will not pull the letters, but may polish them away. Such areas are best done by hand and then blended into the final machine finish.
Another caution: Wheels can grab and throw material being polished with some violence. This is hard on parts, and hard on you if you are in the way. Always be aware that this can occur, especially with small parts which can be almost impossible to find. And always polish on the lower half of the wheel. Always polish with sharp edges pointing in the same direction the wheel is turning.
Polishing wheels are not designed for cutting or removing metal, but for polishing the surface as the name implies. Any attempt to use a polishing wheel to remove a pit will only result in an ugly depression. The edges of the pit will be pulled out, making the flaw more obvious.
Deep pits or gouges can be welded and cut back down to the surface. The possibility always exists that the metal used in welding may not exactly match the base metal, and the blue of the weld may not match the blue on the remainder of the work. Gouges can be removed by draw-filing. When draw-filing a gouge, blend the filing area into the metal around it. The deeper the gouge the larger the blending area. On octagonal barrels, this blending may have to be full length to preserve the points where the flats join. Because of this, the width of the flats may vary slightly. This difference is usually not noticeable.
Letters and numbers must be hand polished if their sharp impressions are to be preserved. File and polish up to the stamping, but not the stamp-ing itself. If rust pitting, dinging, or damage to the stamping has occurred, it may be better to leave this imperfection in the stamping area rather than to try to remove it. Most minor flaws will be unnoticed when mixed in with letters and numbers, and this is certainly less noticeable than having half the letters and numbers polished away. A very light touch with your final wheel will blend this area into the surrounding finish without damage to letters or numbers. Another important point to remember is the BATF rule. It is illegal to remove, alter, or obliterate the serial number!
Of course, any firearm polishing is likely to be a combination of both hand and machine work. Use machines where possible for speed, and use hand work for detail. There is no need to spend hours laboriously removing machine marks on a barrel, when a barrel spinner and square wheel can do a really good job in minutes. Likewise, there is no need to round off edges, ruin letters and numbers, or dish out holesnot when a few minutes of extra care will keep them sharp, clean, and square.
Final Finishing Techniques
Bead- or sandblasting is not a polishing technique. It will not hide imperfect or sloppy polishing, and, in fact, will bring these imperfections out and make them more visible. Blasting is also an indication of lazy or incompetent work. This type of final finish has its place, but it should not be used to hide sloppy workmanship.
A light beadblast will give a rust blue appearance to a well-polished gun and enhance the appearance. Sandblasting will give sharp contrast between high polish and dull surfaces. Bead- or sandblasting will kill glare on sighting surfaces, add contrast to otherwise boring blueing jobs, and can give the owner a unique-appearing firearm he can be proud to show.
Wire wheels can also give unusual finishes to a final polish. A soft wire wheel, when lightly run over a barrel (crossing at 45-degree angles), can give a good approximation of some factory finishes. A rough wire wheel used at intersecting 90-degree angles will give an entirely different finish. Scotch-brite will give yet another.
No one person has the patent on metal finishes. What works best for you should be what you use.Click here for American Gunsmith Website