Over the years, bad habits creep into our work procedures. Periodical review of our techniques is needed to assure us that these “bad habits” are not allowed to continue to effect the quality of our work. In this article, we will continue our Back to Basics Series with an article on Filing techniques.
Filing is a basic technique used by jewelers, and the file is one of the most important shaping and finishing tools. Files are used for cutting, shaping, and smoothing metal. Because the file is such a simple looking tool, most people think there is no right way to use it. However, this is not true.
Filing incorrectly waste time, causes unnecessary work, and waste precious metals. Proper filing, to a large extent, determines whether the finished jewelry will look professional or amateurish.
Accurate and rapid filing can only be developed through study and practice. For speedy filing the answer is in method, not muscle. Work with steady, even, long strokes. Frantic aggressive filing or short, broken, “fiddling” strokes will produce in-accurate results.
All files are designed to cut on the forward or push stroke. An efficient file stroke is smooth, steady, and even, using the full length of the file. The backward or pull stroke does not cut; it only repositions the file to start the next cutting stroke. Many jewelers develop the habit of lifting the file from the metal surface for the return stroke. Others leave the file in contact but allow it to lightly slide back. Either method is fine, however when working in areas of critical fit or precise edges, lift the file on the return stroke and take careful, deliberate cutting strokes. This permits constant visual inspection.
Hold the file handle firmly with your index finger extended on top of the file. This permits you to apply the needed pressure during the cutting stroke. Line up your hand and wrist in a straight line from the file tip to your elbow. As you file, do not bend your wrist. Only your elbow and shoulder should move during filing, not your hand or wrist. Whenever exerting forward pressure on the hand, keep the wrist straight as possible. Putting pressure on the wrist in a bent position over time will develop corporal tunnel syndrome.
Files come in many widths, lengths, shapes, and cuts. Cuts range from the finest #8, to the coarsest #00. (This numbering sequence is the opposite of saw blades) Hand files and Needle files are the two types most commonly used in jewelry work. Hand files are used for general filing. The most useful cut is a #4 with a #2 cut used for heavy coarse filing.
Needle files shape and smooth areas that are unreachable with the larger hand files. A common mistake made by jewelers is using too coarse of a needle file. A #2 cut needle file is too coarse for jewelry work. It leaves deep file marks in the metal, which are difficult to remove from the tight spaces where needle files are used. When attempting to remove them the clean straight edges or contours developed by filing are lost, resulting in a mediocre job.
A #4 cut needle file should be saved for times where heavy filing is needed in tight areas. A #6 cut needle file is used for general filing. Often a jeweler can go straight to polishing with tripoli after using a #6 file. This will save not only time but also reduce waste material. More importantly, the clean straight edges, contours, and sharp corners produced with the file are not lost in the sanding process. This results in a more professional looking finished piece of jewelry.
When filing flat surfaces or straight lines, hold the work steady. Move only the file. A flat-faced file is needed. Using the flat side of a half-round, barrette, equaling, or other file is a matter of personal choice.
Filing an outside curve (convex surface) is similar to flat filing and the same file is used. As the file moves forward, bend your wrist slightly and lift your elbow to follow the contour of the surface. Use long strokes, and keep the file moving in a smooth continuous curve or you will develop flat spots on the jewelry.
To file an inside curve (concave surface) a file with a rounded face is need. You can use a half-round, oval, round or crossing file. Allow the file to roll from side to side as it is pushed forward. This not only keeps the contour of the curve, but also prevents cutting irregular flat spots in the edge of the metal.
You should always take great care when filing that you do not remove too much metal. It is impossible to replace the metal removed. When filing to remove excess solder, often the mistake is made of filing too much resulting in thinning the metal. Stop filing when the outline of the solder is just barely visible. Sanding to prepare the metal for polishing will remove the remaining solder. If you continue to file until all evidence of the solder is removed; when sanded the metal will be thinned more than necessary.