Spraying standardisation

The most common of the spray tests is the salt-spray or salt-fog test which was developed originally by Capp in 1914 for studying the protective values of metallic coatings on steel under conditions that he hoped would simulate exposure to a sea-coast atmosphere. Since then the test has been used for a number of purposes, for many of which it is not well suited Although there is no standard size or shape of salt-spray box certain other features of the test have been standardised in ASTM B117 1990. Various... 

There are many different spray guns available and the type used does not seem to be critical , but the small type known as an artist s air brush is suitable for small components, and standard paint spray guns for larger components. The operator should standardise on one type of gun and nozzle for the sake of consistency. Where a large number of similar components are to be sprayed it is desirable to set up a semi-automatic or automatic system to ensure uniformity. 

Standardisation may focus on the testing equipment, such as chambers for salt spray testing, and on the testing protocol. In order to limit the dispersion of the results, the testing conditions define as precisely as possible the sample preparation, the chemicals, the test duration, the expression of results, etc. 

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