Crimson Tree Resin is resin of the braided crimson tree.
Crimson tree resin instantly oxidizes into hard, green crystals on contact with Pandoran air. Braided resin can be dissolved into a tough and lustrous varnish.
Resin is a viscous liquid that plants secrete to defend themselves against injury and predators. The Na'vi greatly value resin in crafting, using it to make glues and varnishes as well as polishing the hardened resin crystals for decoration.