Heat marks form on wood surfaces when you place something hot directly onto the wood. The heat causes the fibres in the wood to swell and water becomes trapped in the tiny gaps, discolouring the wood's surface. You should remove the heat mark as soon as possible after it forms, but be aware that it can take several attempts in order to fully remove it. If you do not remove the heat mark quickly after discovering it, the mark can become permanent.
Mix enough cigarette ashes with 1 tbsp lemon juice to make a paste. The mixture should be the consistency of thick pancake batter.
Use a soft cloth to gently rub the cigarette ash and lemon juice paste into the heat mark. The citric acid from the lemon juice helps the cigarette ash to work more effectively on the heat mark and release it from the wood. Repeat as needed until the heat mark disappears.
Polish the wood with wood polish as you would normally once the heat mark has lifted.
You can also use cooking oil instead of lemon juice, but the citric acid from the lemon juice is more effective. To prevent heat marks, use trivets, hot pads or coasters under hot items. Avoid setting hot items directly onto the wood surface. For lacquered wood, use a mixture of non-gel toothpaste and baking soda to rub over the heat mark. When the toothpaste and baking soda mixture warms, wipe the area clean and polish the wood as you would normally.