3.1 It is difficult to overemphasize the importance of the spall test. Porcelain enameled aluminum that fails this test will probably spall in service if subjected to moisture or weathering.

1.1 These test methods cover accelerated determination of the resistance of porcelain enamel coatings on aluminum alloys to spalling from exposure to moisture or weathering. Test Method A,2 using a 5 % solution of ammonium chloride, requires 96-h immersion while Test Method B,3 using a 1 % solution of antimony trichloride, is completed after 20 h of immersion. The spalling tendency is evaluated by the same criteria in both methods. While either method is suitable for magnesium silicon alloys, such as 6061, Test Method B is preferred for simple alloys or commercially pure aluminum, such as 1100.

1.2 The test methods appear in the following order: