Salt spray testing is a test method for evaluating a product or a coating's resistance to corrosion in the face of extended exposure to a saline, or salted, spray.
A cost-effective corrosion testing method, salt spray testing is conducted in a closed salt spray chamber where the sample is subjected to a sodium chloride fog, an extremely corrosive atmosphere. The length of exposure time is determined by the material, the coating, and the standard. For example, the standard ISO 9227 requires 720 hours in NSS, or neutral salt spray. After exposure, Element experts examine the sample for the presence of oxides and evaluete its corrosion-resistance performance.
Types of salt spray testing: NSS, ASS, CASS
Most frequently used to measure the corrosion-resistance of coatings and paints, the salt spray test can be adapted to different corrosivity levels to simulate different environments—the difference between the Indian Ocean and the Great Salt Lake, for example.
Variations include: A standardized 5% solution of NaCl, known as NSS or neutral salt spray; acetic acid or ASS test, and acetic acid with copper chloride or CASS test. The solution is chosen based on the specific coating being evaluated, such as electroplated copper-nickel-chromium, electroplated copper-nickel or anodized aluminium.
Related salt spray testing lab standards: ASTM B117 and beyond
A number of corrosion testing standards from a range of industries require the use of salt spray testing methods. These include: ASTM B 117, ASTM B 368, ASTM D1735, ASTM G 85, ISO 9227, MIL-STD-1312-01, MIL-STD-202G, MIL-STD- 810, NASM 1312- 1DIN 50021, ISO 9227, and ISO 4628-3, ISO 4042, and ISO 10683. For more details on these standards, click on the links below.