Give projects bright colors, funky designs…or write your name on it! For use on ceramics, glass, metal and terra-cotta. Thermo-hardening after baking. Includes 5.3-ml. pens in assorted permanent colors: purple, black, pink, yellow, light purple, brown, green, blue, red and orange. (10 pcs. per set) Safe and non-toxic. Conforms to ASTM D-4236. Press the tip of the marker until the ink flows.