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The Tru Temp black oxide process from Birchwood Casey is a two-stage process that enables the use of milder chemicals at lower temperatures than ordinary black to protect working parts from rust and corrosion. The non-demensional finish is suitable for tractor, trencher, backhoe and grade manufacturers of precision machined surfaces, including PTO components, split shafts, augers, universal joints, couplings and valves.
The Tru Temp process produces a durable, satin black magnetite coating 20-millionths thick (0.5 micron), and is said to have no effect on component hardness or tensile strength. It is designed to work effectively with mild alkaline chemistry that does not embrittle metal or create salt bloom in or around part recessed areas. According to the company, the finish can withstand as many as 200 hours of neutral salt spray (ASTM B 117) or several hundred hours of humidity (ASTM D 1748).
The solutions contain no EPA-regulated chemicals and no waste treatment equipment is usually required.