These coasters are printed on thick pulpboard (like the coasters you see in bars, only better). We generally use 4" round coasters, but that depends on our mood.*

"Road tests" of these coasters have proved their sturdiness. We held a coaster under running water and let it dry. Other than minimal warping, the coaster proved to be as good as new. Red wine (and other colored beverages) will, of course, stain coasters. The ink stands up to water and alcohol without any problems.

*We won't mention what mood we have to be in to use the square ones.