Salt a napkin to keep your cocktail glass or beer from sticking to it | Lifehacker #tips. LPT: Sprinkling a little salt on a paper napkin will stop it from sticking to your bottle/glass when you pick it up. | Reddit.
Salt is basically a rock. Actually it IS a rock. When you put it on a napkin or coaster is acts as a buffer between the coaster or napkin and the bottom of your glass while allowing the napkin or coaster to continue soaking up the condensation that trickles down the outside of your glass.