White discolorations on finished wood furniture indicate damage from either heat or water -- a hot pizza box or a glass of ice water are equally suspect. In either case, the marks can often be repaired with household substances such as mayonnaise, baking soda or an oil-and-vinegar solution.
White marks often indicate that some moisture is trapped in the finish on the wood furniture; this can happen easily if a glass used without a coaster sweats or drips on the table, and the water isn't wiped up immediately. A hair dryer helps remove fresh moisture-based white marks. Set the hair dryer to a low heat setting and hold it 8 inches or so from the white spots, moving the hair dryer slowly to prevent overheating the wood finish. Allow the furniture to cool again before placing any objects atop the heated area.
Baking Soda Scrub
Mix a little water into a tablespoon of baking soda, wetting it just enough to create a paste. Apply a little of the baking soda paste onto a soft white cloth, rubbing it into the white marks with a circular motion. Push the paste aside to check your progress, stopping when the marks are gone. Wipe up the excess paste with the cloth when finished, catching the residue in your hand or in a trash can. A non-gel white toothpaste can be used in place of baking soda and water; both the baking soda paste and toothpaste act as mild abrasives that buff out the white markings.
Pass the Mayo
Mayonnaise also removes white rings or spots from wood furniture. Apply a little mayonnaise to your finger or a soft white cloth; then rub it into the affected area of the wood. Wait at least 30 minutes before wiping it away. If the mark remains, allow the mayonnaise to sit for another hour. Wipe it away with a slightly damp cloth afterwards.
Equal parts olive oil and white vinegar team up to remove white spots while acting as a natural furniture polish, free from chemicals. Mix a small amount of the oil and vinegar together, such as 2 tablespoons each, in a jar or container with a tightly sealed lid; then dip a soft white cloth into the solution. Wipe the damaged wood finish with the wet cloth, following the wood grain. Add a drop or two of lemon juice to add a fresh scent to your wood-repair solution. Use the leftovers to wipe down areas of any wood furniture that looks scratched, scuffed or otherwise a bit dried out.