Tru Temp Black Oxide Process

December 13, 2012

Manufacturers are increasingly being asked to remove volatile organic compounds (VOCs) and EPA regulated metals from their facilities. The TRU TEMP low temperature black oxide system from Birchwood Technologies is reportedly safe and simple to operate and serves as a direct replacement for conventional high temp black oxide. The process utilizes a chemical reaction that is based only on sodium-salt compounds, and is free of EPA regulated metals. In addition, the TRU TEMP process line can easily be configured to avoid the use of high-VOC compounds.

The TRU TEMP finish is a durable, satin black magnetite coating, 20 millionths thick (0.5µm), with no effect on material hardness or tensile strength. The finish withstands up to 100 hours of neutral salt spray (ASTM B 117) or several hundred hours of humidity (ASTM D 1748), verified by independent testing. The TRU TEMP finish complies with all current Mil Specs (ELV, RoHS; MIL-DTL-13924D, Class 1; ASTM 2485) and protects the metal surface during shipment and storage and also in service.

In addition, the TRU TEMP black oxide enhances overall quality and visual appeal, thereby allowing critical components to be marketed as premium grade products that command higher selling prices than non-blackened or oiled grade components. The patented TRU TEMP process utilizes a unique two-stage oxidation process using milder chemicals and much lower temperatures (90 degrees lower) than ordinary black oxide. It operates effectively with mild alkaline chemistry that does not embrittle metal or create unsightly salt bloom in and around part recessed areas.

Additional TRU TEMP advantages include short processing time of just 25 minutes, and low operating cost – chemical costs average $.06 to .08 per pound of finished work. Large parts can be processed on racks or in baskets; small parts can be processed in bulk loads. New process lines, in all sizes, are available from Birchwood Technologies at modest cost, and most existing tank lines can be retrofitted for TRU TEMP at low cost.

Related Glossary Terms

  • black oxide

    black oxide

    Black finish on a metal produced by immersing it in hot oxidizing salts or salt solutions.

  • hardness


    Hardness is a measure of the resistance of a material to surface indentation or abrasion. There is no absolute scale for hardness. In order to express hardness quantitatively, each type of test has its own scale, which defines hardness. Indentation hardness obtained through static methods is measured by Brinell, Rockwell, Vickers and Knoop tests. Hardness without indentation is measured by a dynamic method, known as the Scleroscope test.

  • tensile strength

    tensile strength

    In tensile testing, the ratio of maximum load to original cross-sectional area. Also called ultimate strength. Compare with yield strength.


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