Surface pretreatment prior painting

In order to obtain maximum corrosion protection for painted metal articles, the metal parts are pretreated with an inorganic conversion coating prior to the painting operation. These zinc or iron phosphate coatings greatly increase both paint adhesion and corrosion protection. Traditionally, a chromic acid post-treatment has been applied to these phosphatized metal surfaces to further enhance corrosion protection. 

By far, the most common pretreatment for steel constructions prior to painting is blast cleaning, in which the work surface is bombarded repeatedly with small solid particles. If the individual abrasive particle transfers sufficient kinetic energy to the surface of the steel, it can remove mill scale, rust, clean steel, or old paint. The kinetic energy (E) of the abrasive particle before impact is dehned by its mass (M) and velocity (V), as given in the familiar equation ... 

A well known metal adhesion application is in washed primers. Application information is available. Additional information is provided in the general references and Refs. 37 and 38. The Navy has long recognized the need to pretreat a metal surface prior to painting to inhibit corrosion and promote adhesion and specifies wash primers in MIL-F-15328C and MIL-C-8514B. 

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