graying

Strong sunlight on unprotected wood destroys the wood component lignin. Wood outdoors acquires a relief-like, weathered, gray surface as the destroyed lignin is washed out. In this state, wood with a low resistance is no longer protected against the ingress of water and encourages the colonization of wood-destroying fungi. Tropical woods are an exception. Teak in particular develops a homogeneous silver color without sacrificing resistance.