This section is from the book "Soldering For Workshop, Farm And Home", by John Bonert. Also available from Amazon: Soldering For Workshop, Farm And Home - Information On Soft And Hard Soldering - Projects For The Workshop Explained And Illustrated.
Files are a very necessary part of every tool kit and should receive the same care that all good cutting tools require. The cutting teeth of a file are made to cut on the forward stroke. Pressure should be applied on the forward stroke. On the back stroke allow only the weight of the file but do not lift it from the work. Keeping files where they will rub against each other will surely injure the cutting edges. The best way to keep files is to have a rack such as is illustrated in Figure 21 which can be fastened to the wall.
Never try to file hardened steel because it will surely make the file unfit for future use. Files can be cleaned with a stiff steel brush but after filing solder or lead a brush is not very effective. The soft metals will fill the spaces between the cutting edges of a file so solid that the brush cannot remove them. File brushes can be bought with a file card included, or one can be made very easily. Figure 22 shows how a file card or cleaner can be made. A piece of iron or soft steel wire or larger in diameter is hammered flat on one end to almost a sharp edge and a loop is made on the other end. The flattened end will have to be filed to a straight edge.
The cleaner is now ready to be used. The file to be cleaned is held in the left hand and rested on the bench. Place the cleaning tool on the surface of the file and with pressure move in a back and forth direction parallel to the teeth of the file until the teeth are cut into the flat end of the cleaner. Start at one end of the file and push the cleaner across the file. This will cut out all the metal or other material that has collected between the teeth. Now move the cleaner to the next set of teeth it will cover and repeat the operation. This is continued until the file has been cleaned for its entire length. For coarser or finer files the end of the cleaner will have to be filed again to a straight edge and the operation of cutting teeth on the cleaner will have to be gone through again. One method that will help to keep files clean is to rub ordinary chalk over the file. This fills the spaces between the teeth with the powdered chalk and helps considerably to keep the file from filling up especially when filing steel.