Moisten a soft rag with mineral spirits
Spilled water or a wet glass can leave a white stain on wood furniture. Often, complete stripping and refinishing are the only solution. But there are two solvents that can sometimes remove water marks in a few minutes without harming the finish. Both solvents give off nasty fumes, so work outside in a well-ventilated area. If you think the piece might be especially old or valuable, consult an antiques dealer before trying these remedies.
First, rub the stain with a soft rag dipped in mineral spirits. If the original finish has a coating of wax over it, there’s a good chance that only the wax has turned white. Mineral spirits removes wax without harming the underlying finish. Have patience; the mineral spirits may take a few minutes to soften the wax. If the stain disappears but leaves the rubbed area looking dull, clean the entire surface with mineral spirits and apply a new coat of furniture wax.
If mineral spirits doesn’t work, gently wipe the stain using a soft rag lightly dampened with denatured alcohol. Alcohol can damage some finishes, so test it on an inconspicuous spot first. Stop every minute or so to examine the finish to make sure you’re not damaging it. Again, have patience. Sometimes alcohol can draw out moisture that’s trapped in the finish, but it works slowly. If you don’t see any results after five minutes, refinishing is the only way to remove the mark.