Self-hardening, 2 part product (A & B) must be mixed thoroughly. Putty like feel. * pen working time about 2-3 hours. Cures hard overnight (24 hour full cure). * 0% shrinkage. * Strongly adheres to almost any clean surface . . . including ceramic, fiberglass, foam, glass, metal, plastics, resin, stone, wood, and more. * Can be seamlessly feathered before set-up, or sanded, tapped, lathed or otherwise tooled after.