Paragraph 82. All saws should be kept perfectly clean, free from glue, rust or anything else which would give the sides of the saw a rough surface. Saws should be wiped frequently with an oiled rag (do not use linseed oil). If any spots of rust appear they should be rubbed off with powdered emery, pumice stone, or with a piece of well-worn sandpaper and a little oil. Care should be exercised never to allow the teeth of a saw to strike against any kind of metal, such as the vise jaw, a nail or a screw. If it is necessary to saw a board which is covered with dirt, cement, or any other substance which is likely to dull the saw, the board should be carefully cleaned along the line where the saw cut is to be made before the work is attempted. It is very much easier and cheaper to keep shop saws sharp and in good order by proper care than to have them re-sharpened.