Is there a problem with food NOT stuck on to lettering. Washing off dirt on one's hands.
using magnets and loose leafs on Shabbos;
Making a Bruise or Using a Toothbrush When One's Gums Might Bleed. Using Floss, Toothpicks, and Dealing with Blood from a Cut;
working with items that are made to go in and out on a constant basis;