Hi Bob. It hasn't caused me a problem in the last 10 to 15 years. It makes a big difference on a hacksaw blade in reducing heat buildup which is the big reason that carbon steel hacksaw blades become dull. You can try it on one file, but I think you will like it. You can always clean it off. Also I used the grill from an old air conditioner, after I cut it in half, to hold my files. You have to support it horizontally and the file handles have to be on tight, but you can store a lot of files in a small space.