Chamber construction, testing procedure and testing parameters are standardized under national and international standards, such as ASTM B 117 and ISO 9227.
These standards describe the necessary information to carry out this test; testing parameters such as temperature, air pressure of the sprayed solution, preparation of the spraying solution, concentration, pH, etc.
Daily checking of testing parameters is necessary to show compliance with the standards, so records shall be maintained accordingly. ASTM B 117 and ISO 9227 are widely used as reference standards. Testing cabinets are manufactured according to the specified requirements here.
However, these testing standards neither provide information of testing periods for the coatings to be evaluated, nor the appearance of corrosion products in form of salts. Requirements shall be agreed between customer and manufacturer.
In the automotive industry requirements are specified under material specifications. Different coatings have different behaviour in salt spray test and consequently, test duration will differ from one type of coating to another.
For example, a typical electroplated zinc and yellow passivated steel part lasts 96 hours in salt spray test without white rust. Electroplated zinc-nickel steel parts can last more than 720 hours in NSS test without red rust (or 48 hours in CASS test without red rust).
Requirements are established in test duration (hours) and coatings shall comply with minimum testing periods.
Electroplated and yellow chromated bolt with white corrosion
Zinc flake coated bolt with red rust after testing
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