Weber Turpenoid Natural An effective nontoxic brush cleaner, gentle brush reconditioner and medium. Turpenoid Natural was designed for artists and students as a safer alternative to traditional and harmful solvents associated with oil painting. AP Nontoxic, nonflammable and with no harmful odors, Turpenoid Natural is safe for artists of all ages and will not irritate skin. It will effectively clean and gently recondition brushes and rinses out with plain water. Turpenoid Natural may also be used as a medium within recommended guidelines. When used as a medium, paint to Turpenoid Natural ratio should not exceed 4:1.