Testing and Caring for Files
To test a file hold it so that the light will be reflected sharply from the teeth and observe whether their edges are flattened and appear as white lines. If so, the file is dull and should be recut if of considerable size and value.
Files should not be thrown into drawers and mixed with other tools, but should be carefully set in racks or drawers for the purpose. A mechanic would not throw a straightedge into a drawer containing other tools, and a file should be given similar consideration, as every nick in the teeth impairs the efficiency of the file.
Files may be sharpened by dipping them into sulphuric acid, but care must be taken not to permit the acid to come into contact with one’s clothes or person. Water is used to wash off the acid.
Files should be provided with individual handles. This prevents injury to the hand of the worker and aids in the proper use of the file. Handles should be carefully fitted and be made of a size proportionate to the file. In removing a handle from a file, strike the handle at the end nearest the file, by sliding a piece of hard wood along the surface of the file, as the blow is struck with it. Do not use another file or metal object in thus removing a handle, as it will injure the latter.