The purpose of file purpose of filing is to remove excess metal. Jewelry makers use different grades of file to achieve different finishes, but large escapement and engineering files are not suitable for delicate jewelry. Filing is also the first step toward finishing a piece, and it is important that you should use the files in the correct sequence, so that any marks made by one are removed by the next. The finished article should not bear any file marks. You should always take great care when filing it is impossible to replace the metal removed by each stroke of a file.
Files are graded by the coarseness of the cut. A "zero" or 0 file is the coarsest, 2 gives a medium cut, and 4 is the finest. Some needle files are graded down to 6. If quite a large amount of metal has to be removed, a large 0 file will do the work most efficiently, but any further filing should be done with a finer grade, and this should be followed by an even finer needle file.
Choose a correctly shaped file for each job. On an inside curve, you should use an oval or a half-round file. If you need a crisp right angle, use a square file. Grooves are best worked with a triangular file. A groove for Chenier can be filed with either a round file or a joint round-edge file. Some files have "safe" edges, so if you need to file close to an area that you do not want to mark, you can work with the "safe" area next to the area to be protected.
When you use a file, it is important to keep the direction level. For example, if you are straightening a line, use a flat file and keep it absolutely parallel to the line. If you do not, the corners at the ends of the line will tend to curve and drop below the line.
Files usually cut in only one direction, so place the article on the bench pin and hold it steady with one hand while you hold the file in the other hand, and then work with a forward cutting movement. Rubbing a file back and forth over a piece is ineffective.
Using wet and dry sandpapers
After filing you should clean the area with wet and dry sandpapers. These are available in grades ranging from 240, through 400 and 600, to 1200, and you should keep a variety of grades in your workshop so that you can work through each grade if you want a highly polished finish. As their name suggests, these papers can be used with or without water. Water helps to keep the surface smooth by washing away the metal particles as they are removed by the paper. When you are sitting at your work area, however, it is often impracticable to have a bowl of water in front of you and water dripping on the bench. The papers are, therefore, often used dry.
When you are rubbing a flat metal surface with wet and dry sandpapers, place the paper on a flat surface an old tile or a piece of mirror, for example, or a metal flat plate and rub the work along it.
Making an emery board
Small sections of paper can be cut from a large sheet and wrapped around a file to remove file marks. Papers can also be glued to wooden sticks. Take a small piece of wood, approximately 1/4 x 2 x 8 inches and glue a section of wet and dry sandpaper, about 2 x 5 inches, around one end of the stick. The wood creates a firm, flat base that can be pulled across the metal. This is used dry.
A burnisher is a highly polished, hard steel tool that is rubbed firmly back and forth on metal to create a polished, shiny surface.
A curved burnisher can be used to polish the top edge of the bezel for a cabochon stone setting. This is a delicate operation, but you do need to exert quite a lot of pressure on a burnisher to polish a surface, and it is easy to slip and damage the stone, especially a soft stone such as an opal, which could crack under sudden pressure. Use your other hand as a brake on the burnisher to avoid damaging the stone.
Use your burnisher to remove scratches caused by slips of engraving tools or other little mishaps. Put a drop of oil on the affected area and rub the burnisher sideways, along the direction of the scratch. If you rub the burnisher across the direction of the scratch, you may make it worse. Finish off with fine-grade wet and dry sandpaper, again working in the same direction as you smooth over the burnished area.
Writer – Jinks McGrath