I can’t claim credit for this one. Phyllis taught it to me, and it’s so brilliant I have to share it. If you’re like me and use your rulers for marking, drafting, and tracing, you’ll find after a while you’ll have all sorts of residual gunk on the edges. I always used window cleaner, but they never came completely clean. Well, instead of that, just use plain old rubbing alcohol. I soak a scrap of muslin with it (you can use cotton balls, but muslin won’t leave any lint). Rub it over the edge and it will remove pencil, pen, Sharpie ink, and anything else, leaving you with a clean ruler. Having ruined light colored fabric because I got ruler gunk on it, I’ve taken this one to heart. Thank you Phyllis!