Test Method Used in Leather Tanning

A new ASTM International standard will provide a test method related to unfixed chrome concentrations in Wet Blue. The standard, soon to be published as D8451, was developed by ASTM’s committee on leather (D31).

According to ASTM International member Okey Abara, Wet Blue is an intermediate product used for processing natural hides. It is produced when a tanning agent chemically binds to the collagen in hide.

“There is a need for an analytical method to test for the amount of the tanning agent absorbed by the hide but not chemically bound to the hide substance: that amount is termed ‘unfixed chrome,’” Abara says. “This new standard offers a way to monitor the amount of unfixed chrome, the amount of tanning agent that is not bound to the hide substance.”

Abara says that the standard will be useful for both producers and users of Wet Blue, as knowing its amount of unfixed chrome can improve efficiency. “Adjusting the amount of offered chrome to minimize the amount of the tanning agent not bound to the hide substance reflects potential cost savings for the Wet Blue processor,” notes Abara. 

Abara encourages participation from all interested parties from any aspect of the leather industry in developing and reviewing viable, user-friendly, and environmentally-friendly standards. 

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