This specification establishes the engineering requirements for producing an acid-type, anodic coating on magnesium alloys and the properties of the coating. This process has been used typically to increase corrosion and abrasion resistance and to provide surfaces which will ensure maximum paint adheresion, but usage is not limited to such applications. This process is applicable to all magnesium alloys provided proper allowance is made for dimensional change. It should not be used on parts which will be flexed in service. Abrasion resistance is not as high as that provided with the alkaline electrolytic treatment of SAE AMS 2476 but, when similarly painted or coated, other properties are equivalent. SAE AMS 2478 coatings often exhibit poor adhesion to surfaces of castings. Thin coatings in accordance with SAE AMS 2479 are preferred for castings.