Fully hydrogenated jojoba esters are most often small beads used to exfoliate the skin. Some methods of hair removal also exfoliate the skin. Pumice is considered a good material to exfoliate the skin of the feet. The bark is vertically fissured and tends to exfoliate in ribbon-like strips. The bark is gray-brown and may exfoliate in small irregular plates. Various topical treatments are available to "exfoliate" the scales. Combinations of different solvents also exfoliate boron nitride better than individual solvents. Molting brown bears in Alaska have been observed using rocks to exfoliate. The etymology of the word "exfoliate" comes from the Latin "exfoliare" (to strip off leaves).