A wood table may last for generations with optimal care, but life happens. A hot casserole dish, cup of tea or takeout box placed directly on the table may leave behind heat marks that mar the table's finish. Thankfully, these unsightly white marks cause no permanent damage to the wood itself; the white spots are within the table's finish and can be removed with a little care and attention with no wood refinishing required. One or more methods may be used to render those spots invisible again; stop once the table finish looks as it should.
Wrap a non-abrasive cloth over a fingertip and apply a dab of white toothpaste over the tip of your covered finger. Rub the affected area gently, following the wood grain as much as possible. Wipe off the toothpaste with a damp non-abrasive cloth. If the spot is still somewhat visible, rub more toothpaste over the area, then wipe it away again with a damp cloth. Buff dry with a fresh soft cloth. Toothpaste contains mild abrasives that help buff out the damage to the furniture finish.
Mix a small amount of cigar or cigarette ashes with just enough lemon juice to make a paste on a disposable plate or in a small container. Wrap a soft cloth over your fingertips and dip them into the paste, then buff the paste over the white marks. Wipe the area again with a soft, damp cloth, followed by a dry cloth.
Rub the affected area gently with 0000 steel wool if any white marks remain, following the grain of the wood. Check your work frequently to avoid removing more of the finish than necessary.
Polish the tabletop with furniture polish after all heat marks have been removed.