Van Sickle Tractor, Equipment and Industrial Enamel Clear Hardener/Catalyst is an IPDI Urethane additive. Hardener Catalyst Enamel Additive To Paint, For Tractors, Farm Equipment, Machinery, Tools, Vehicles & Other Industrial Applications. Size: 8 ounce. Color: Clear Hardener/Catalyst. Hardener catalyst enamel additive to paint. Made in USA.