Birchwood Technologies’ Tru Temp low-temperature black oxide system uses no EPA-regulated metals and can be configured to avoid the use of volatile organic compounds (VOCs). According to the company, the two-stage oxidation process uses mild alkaline chemicals and will not embrittle metal or create salt bloom in or around part recessed areas. The process uses a chemical reaction based on sodium-salt compounds and is a replacement for conventional high-temperature black oxide.
The finish is a satin black magnetite coating 20 millionths thick (0.5 micron) with no effect on material hardness or tensile strength, the company says. The finish is said to withstand up to 100 hr. of neutral salt spray (ASTM B 117) or several hundred hours of humidity (ASTM D 1748).