Salt spray (fog) cabinets – SASSC
The salt spray test is a standardized test method used to check corrosion resistance of coated samples. Coatings provide corrosion resistance to metallic parts made of steel, zamak or brass. Since coatings can provide a high corrosion resistance through the intended life of the part in use, it is necessary to check corrosion resistance by other means. Salt spray test is an accelerated corrosion test that produces a corrosive attack to the coated samples in order to predict its suitability in use as a protective finish.
The appearance of corrosion products (oxides) is evaluated after a period of time. Test duration depends on the corrosion resistance of the coating; the more corrosion resistant the coating is, the longer the period intesting without showing signs of corrosion. Nevertheless, salt spray test iswidely used in the industrial sector for the evaluation of corrosion resistance of finished surfaces or parts.
The apparatus for testing consists of a closed testing chamber, where a salted solution (mainly, a solution of 5% sodiumchloride) is atomized by means of a nozzle. This produces acorrosive environment of dense saline fog in the chamber so that parts exposedin it are subjected to severely corrosive conditions.
Tests performed with a standardized 5% solution of NaCL are known as NSS(neutral salt spray). Results are represented generally as testing hours in NSS without appearance of corrosion products (e.g. 720 h in NSS according to ISO9227). Other solutions are acetic acid (ASStest) and acetic acid with copperchloride (CASS test), each one chosen for the evaluation ofdecorative coatings, such as electroplated copper-nickel-chromium, electroplatedcopper-nickel or anodized aluminium.