Surface Preparation of Stainless Steel Prior to Painting

Military specification MIL-T-704, Treatment and paint of materiel, requires the passivation of corrosion-resisting steel surfaces before painting. It also states surfaces to be painted shall be treated with wash primer conforming to DOD-P-15328, Primer wash pretreatment Formula No. 117 for metals, metric, or MIL-C-8514, Coating compound, metal pretreatment, resin- acid. Federal, state and city environmental andor health regulations may prohibit the use of hexavalent chromium-one of the components of the passivating formulation used for the treatment of corrosion-resisting steels. Many companies are not passivating the corrosion-resisting steels before the application of wash primer. Based on the above, we started a laboratory investigation to determine if the elimination of the passivating procedure will have an adverse effect on the camouflage paint system. From the information obtained, it is recommended that consideration be given to the elimination of the passivation requirement for stainless steel. It is also recommended that more extensive work be conducted to verify these findings.