You're right—mould on wooden chess pieces can be tricky to remove, but it’s not impossible. To remove mould from wooden chess pieces, wipe them with a cloth dampened in white vinegar or rubbing alcohol. For stubborn mould, use a baking soda paste and scrub gently with a soft brush. After cleaning, dry the pieces thoroughly in a well-ventilated area. To prevent future mould, store the chess set in a dry place and consider using silica gel or a dehumidifier.
Removing mould spots from wooden chess pieces seem an impossible task. Chess sets made of wood gradually absorb humidity and develop mould spots that no chemical is capable of removing. The source of this problem is twofold: 1) the chess manufacturers do not use good technology to dry and season wood specially in India 2) mould also is related to the amount of humidity in the air mostly typical of European countries and northern parts of USA where the weather is mostly cloudy and rainy.