What would leave white rings on wood?

Answer by  HelpChat (494)

It's most likely discoloration from cups. Especially coffee cups. The combination of acidic coffee and white milk or cream can leave residue that eats into certain kinds of paint, varnish, or other finishes.

Answer by  sonicfoundation (2597)

White rings on wood can definitely be caused by cups and glasses of cold liquid. The temperature difference between the cup and the air caused condensation which travels down the cup and pools on top of the wood. This warps the wood and caused the white ring. It can be fixed, however.