The first time a guest set a sweating glass on my dining table, I did not think anything of it. Two hours later there was a white ring burned into the finish like a brand. I panicked, googled, and found advice ranging from mayonnaise to a hair dryer to ironing the table. I tried all of it, in that order, and here is what I learned.

Why the ring is white, not ruined

The white mark is not the wood changing color. Moisture got trapped in the finish, the clear coat on top of the wood, and it is sitting in tiny pockets between the finish and the wood. That is why some fixes work: they dry the moisture out or push it back through the finish. The wood underneath is usually fine.

The order to try things

Start gentle and get more aggressive only if you have to:

1. Mayonnaise or petroleum jelly. Smear it over the ring, leave it overnight, wipe it off. The oil pushes into the finish and displaces the moisture. This worked on my light marks.
2. A hair dryer on low. Keep it moving a few inches from the surface. The gentle heat drives moisture out. Do not park it in one spot or you can blister the finish.
3. Toothpaste, the plain white kind. Rub it gently with a soft cloth in circles. It is a mild abrasive that can polish out stubborn marks. Test on a hidden spot first.

What not to do

Do not attack the ring with steel wool, sandpaper, or furniture polish that contains silicone. You will strip the finish and turn a cosmetic mark into a real repair job. I almost made that mistake on an old dresser and stopped myself because the mayo was actually working.

Stop the rings before they start

The real fix is prevention. I use coasters now, obviously, but I also learned that a waxed table is way more forgiving. A coat of furniture wax twice a year gives the finish a sacrificial layer. Rings that used to scare me now wipe off with a damp cloth because they never reach the actual finish.