I don’t care for expensive coasters. Big, heavy, un-absorbent disks or squares may look pretty, but my personal favourites are the freebies I’ve taken from bars. These cardboard and plastic beauties are cheap (free), usually quite absorbent, and easy to store, and — if you make a habit of collecting them during your travels — have the added bonus of making you look like an interesting person who does interesting things. Their only drawback? Some of the smoother ones have a tendency to stick to your glass.
This isn’t a huge problem for hot beverages or cold cans or bottles, but it can be a real issue if you’re drinking a cold beverage in a flat-bottomed glass placed atop a smooth coaster. Thanks to the surface tension supplied by condensation, the damp glass sticks to the smooth coaster, creating a fun little vacuum between the two. Eventually more condensation drips down and breaks the seal, releasing the coaster from your glass, and into your lap. It’s not some great tragedy, but it is annoying.
There are, of course, mitigation strategies. If this problem is plaguing you at home, get rougher, more absorbent coasters. I liberate textured cardboard promotional coasters whenever I see them out in the wild, while Joel snags upholstery and leather swatches, but any absorbent and/or not-so-smooth material will work. Glazed ceramic, glass, and slick plastic coasters are all terrible choices in this regard; choosing slate, unglazed ceramic, naturally absorbent stone, or even knitted coasters can help prevent dreaded stickage. (You can also use a rough-bottomed drinking vessel; the problem occurs when there are two smooth surfaces in play.)
If you’re out and about and find yourself faced with sticky coaster, just season it with a little salt. The sodium chloride crystals will break up the surface tension, freeing your glass. Cocktail napkins are going to cling not matter what — they are almost too absorbent. I embrace their cling, and wrap the napkin up the sides of the glass, so I have a kind of built-in coaster wherever I go. This is particularly helpful at weddings and other social events where you may be walking around with a drink. Not only will you leave nary a wet ring in your wake, but your hand will stay dry too.