To remove water rings from wood, rub a paste of baking soda and water into the wood for five to 10 minutes, and then dry and clean the area with a soft cloth. Alternatively, apply full-fat mayonnaise and let it sit for at least one hour before wiping clean.
To remove water rings from wood less than 50 years old, coat a soft, damp cloth with a paste made from baking soda and water, and then rub the ring in the direction of the wood grain for at least five minutes. Wipe clean, and then seal the finish with wax.
Another option is to use full-fat mayonnaise. Apply the mayonnaise to the stain with a soft cloth and rub the affected area, and then let it sit for at least an hour to dry and free the trapped moisture.
Older furniture may have a shellac or varnish surface and may require a furniture-restoration specialist to remove the stain.