Clearlok Polyurethane Sealant from Birchwood Casey is designed to provide a clear, hard, high-gloss protective finish over trivalent zinc chromate finishes without significant dimensional change.
The Clearlok Polyurethane coating is designed to enhance the durability and sales appeal of the newer trivalent chromates used over zinc plated surfaces. Advertised as completely nonpolluting, Clearlok enhances the appearance and gloss of the final finish while improving corrosion and scratch resistance. Easily applied using a dip tank process, the Clearlok water-based formula dries quickly and rapidly achieves full hardness and scuff resistance.
Rated for corrosion resistance of 48 – 72 hours of neutral salt spray or several hundred hours of humidity exposure, the sealant is easy to use on any production-scale plating line. Supplied as a concentrated liquid, the product is diluted with tap water to form a thin liquid of dipping viscosity. Easily implemented on most zinc plating lines, freshly chromated parts can be immersed immediately in the solution following the last rinse. Racked parts can be immersed, then warm-dried in a conventional drying station. Smaller, barrel-plated parts can be coated in a dip/spin cycle, in which they are unloaded into a spin-dry basket, then dipped in the Clearlok bath, and given a short heated spin to sling off excess liquid and dry the film onto the parts. The result, the company says, is a clear, high gloss coating that dries to a hard, durable film with minimal 0.2 mil thickness.
Clearlok polyurethane is recommended for use on all types of zinc parts including hand tools, decorative or functional hardware, fasteners and automotive components.