Wood oxidation in the form of dark spots or discoloration is a natural process caused by exposure to water and other elements (ie iron in water), and shouldn’t be confused with mold or mildew. These natural signs of aging do not affect the performance of your brush. To exend the life of your brush handle, air dry after use and occasionally apply beeswax or oil. Wood will naturally split and crack over time. Compost head and handle, recycle metal hardware.