Corrosion testing by neutral salt spray test, also known as NSS testing, is a common method used to evaluate the corrosion resistance of materials and coatings. It involves subjecting a test specimen to a salt spray mist, which accelerates the corrosion process and allows for the evaluation of the material’s corrosion resistance.

The test involves placing the test specimen in a sealed chamber, where it is exposed to a fine mist of saltwater spray. The concentration of salt in the spray is typically 5% by weight, which is considered a neutral solution. The test chamber is typically maintained at a temperature of 35°C to 50°C and a relative humidity of 95% to 100%.

During the test, the specimen is periodically examined to evaluate the degree of corrosion that has occurred. The degree of corrosion is typically evaluated using a rating system, such as the ASTM B117 standard, which assigns a numerical value to the degree of corrosion based on the appearance of the specimen.

NSS testing is commonly used to evaluate the corrosion resistance of a wide range of materials and coatings, including metals, plastics, ceramics, and composites. It is a relatively simple and cost-effective method for evaluating corrosion resistance, and it can provide useful information for material selection and product design. However, it is important to note that the results of NSS testing may not always accurately reflect the actual corrosion performance of a material or coating in real-world applications, and other types of corrosion testing may be necessary to fully evaluate the material’s performance.