How to Strip Zinc Phosphate Without Using Chromic Acid

摘要

A. Chromic acid stripping of zinc phosphate has fallen out of use primarily due to the environmental and safety considerations associated with hexavalent chromium. For that reason, alternative methods are necessary in the removal of some of the coatings previously using chromic acid. For zinc phosphate, one recognized substitute is to use a combination of sodium hydroxide and tetrasodium ethylenediaminetetraacetic acid (abbreviated EDTA). Adding 125 grams of each compound to 1 liter of water is recommended by military standard MIL-DTL-16232G. A similar recommendation can be found in federal standard TT-C-490E.