Downloaded from https://www.everyspec.com MIL-STD-81OC 10 March 1975 METHOD 509.1 SALT FOG 1. PURPOSE. The salt fog test is conducted to determine the resistance of equi-o the effects of a salt atmosphere. The specified concentration of moisture and salt is greater than is found in service. The test is appli- cable to any equipment exposed to salt fog conditions in service. 1.1 Application. This test is valuable for determining the durability of coatings and finishes exposed to a corrosive salt atmosphere. For other auulications, this test should be applied only after full rec08niti0n Of its d~ficiencies”and limitationswhich i~e as foliows: 1.1.1 General effects 1.1.1.1 Deficiencies a.
The successful withstanding of this test does not guarantee item will prove satisfactoryunder all corrosive conditions. that the test b. The salt fog used in this test does not truly duplicate the marine atmosphere. effects of a c. It”has not been demonstrated that a direct relationship exists between salt-fog corrosion and corrosion due to other media. d. This test is generally unreliable for comparing the corrosion resistance of different materials or coating conditions, or for predicting their comparative service life.
(Some idea of the service life of different samples of the same, or closely related metals, or of protective coating-basemetal combinations exposed to marine or seacoast locations can be gained by this test provided the correlation of field service test data with laboratory tests that such a relationship does exist, as in the case of aluminum alloys, such correlation tests are also necessary to show the degree of acceleration, if any, produced by the laboratory test.) 1.1.1.2 Limitations a.
The salt fog test is acceptable for evaluating the uniformity (i.e., thickness and degree of porosity) of protective coatings, metallic and nonmetallic, of different lots of the same product, once some standard level of performance has been established. (When used to check the porosity of metallic coatings, the test is more dependable when applied to coatings which are cathodic rather than anodic toward the basic metal.) 509.1-1 METHOD 509.1 10 March 197S