Japanese lacquer is a resin taken from the lacquer tree, Toxicodendron vernicifluum, that is at least ten years old. The resin contains urushiol, which dries slowly in a humid environment and hardens to a glossy, strong, water-proof surface. Lacquer serves as an adhesive as well as a coating. The Shōsō-in contains many leather boxes and wood items that have been coated with lacquer to strengthen and protect their surfaces and shapes. The Shōsō-in also stores masks made with a dry-lacquer technique. Lacquer also forms the base for several decorative inlay techniques, such as heidatsu.