There is many people have no idea with the differences between NSS, AASS and CASS when they do salt spray tests.
NSS: Neutral Salt Spray
AASS: Acetic Acid Salt Spray
CASS: Copper Accelerated Acetic Acid Salt Spray
NSS is the base of salt spray test, it was developed at around 1930s, it is a neutral test which means the test solution pH value is at 6.5-7.2.
AASS is the method in NSS solution with addition of glacial acetic acid in the pH range of 3.1 to 3.3.
CASS is the method in AASS solution with addition of copper chloride in the pH range of 3.1 to 3.3.
How to choose the suitable test ?
It is mainly based on the material and coating of your test samples.
NSS is good for metals and their alloys, most metallic coatings, anodic oxide coatings, organic coatings.
AASS is useful for testing decorative coatings of copper/nickel/chromium, or nickel/chromium. And for testing anodic coatings on aluminum
CASS is useful for testing decorative coatings of copper/nickel/chromium, or nickel/chromium. And testing anodic coatings on aluminum.