Spot cleaning your hat is generally recommended. Fill a bowl with lukewarm water and add in a mild detergent. Dab gently on the dirt spots on the hats with a damp washcloth.  Tougher stains may require the use of a soft bristled brush to remove. Take extra care to avoid your straw hat becoming damp as they’re made of delicate material. Leave the hat to air dry, away from direct sunlight.