ISO9227:2017 also describes the method employed to evaluate the corrosivity of the test cabinet environment.

ISO9227:2017 does not specify the dimensions or types of test specimens, the exposu re period to be used for a particula r pr oduct, or the interpretation of results. Such details are provided in the appropriate produc t specifications.

The salt spray tests are particula rly usef ul for detecting discontinu ities, such as pores and other defects, in certain metallic, organic, anodic oxide and conversion coatings.

There is seldom a direct relation between resista nce to the action of salt spray and resista nce to corrosion in other med ia, becau se several factors in f luencing the progress of corrosion, such as the formation of protective films, vary greatly with the conditions encountered. Therefore, the test results should not be regar ded as a direct guide to the corrosion resista nce of the tested metallic mater ials in all environments where these materials might be used. Also, the perf ormance of different materials during the test should not be taken as a direct guide to the corrosion resista nce of these materials in service.

Neve rtheless, the method described gives a mea ns of check ing that the comparative quality of a meta ll ic mater ial, with or without corrosion pr otection, is maintained.

Different metallic substrates (metals〕 cannot be tested in direct comparison in accorda nce to their corrosion resista nces in salt spray tests. Comparat ive testing is only applicable for the same kind of substrate.

Salt spray tests are generally suitable as corrosion protection tests for rapid analysis for discontinuities, pores and damage in organic and inorganic coatings. In addition, for quality control purposes, comparison can be made between specimens coated with the same coating. As comparat ive tests, however, sa lt spray tests are only suitable if the coatings are sufficiently sim ila r in natu re.

It is often not possible to use results gained from salt spray testi ng as a comparative gu ide to the long-term behaviou r of d ifferent coating system s, since the corrosion stress du ri ng these tests differs significantly from the corrosion stresses encountered in practice.