As with many innovations, the originator of 3M's sticky yellow Post-its didn't know what he had at first. Researcher Spence Sliver was curious about what would happen if he mixed an unusual amount of monomer into a polymer-based adhesive he was working on. The result was an adhesive that would "tack" one piece of paper to another and even re-stick, without leaving any residue on the second piece of paper. The company had no use for the new adhesive until 3M …