Does anyone besides me worry about cross contamination of the grits? I have several of the Festool Systainers for paper storage but I've always worried that the grit from 80 will get onto the 220 paper, or do I just not have enough other things to worry about in life.
While I don't worry about cross-contamination of grits, I don't like to put cutting surfaces together. Remember that special way to fold a sheet of sandpaper so that the rough side always faces a paper side?
This reminds me about a customer who was buying abrasives for his crew. I asked him if he had fine enough grits, and he replied that if his guys need finer grits, they usually just rub two together. I think he was serious, but I'm not entirely sure.