Urushi (漆, urushi) – Natural lacquer made from the sap of the lacquer tree (ウルシノキ, urushi-no-ki; Toxicodendron vernicifluum). Unlike modern “paint,” urushi doesn’t dry by solvent evaporation—it cures by enzymatic oxidation/polymerization in a warm, humid environment (hence the need for a furo/muro). Once cured, it forms a tough, chemically resistant film that can be built in many thin layers, polished to high gloss, or used as an adhesive and binder for powders and pigments. Urushi contains urushiol (ウルシオール), the allergenic component responsible for “urushi rash,” so handling requires serious skin/eye protection and clean working habits.