I worked on a car plant a few years ago in Ohio, my Job Steward showed me a trick w/ a Sharpie. We mark conduit at certain measurements for bending. After you bend the pipe you don't want the ugly "cheater" marks left on the conduit. So, where you have marks, you go back over the same marks in Sharpie again and wipe off w/ your finger while wet. Works like a charm on most things I have dealt w/. Also removed a "bad" autograph on my Auburn helmet w/ "Oops" I think it was called. Works great!