Salt spray testing is a standardised method of checking the corrosion resistance of components and coated samples.
Coatings, which can be organic i.e. paint or powder coatings or inorganic such as galvanising, anodising or plating, are used to protect components that are made from materials such as zinc or steel from corrosion. To predict the suitability of the coating as a protective finish the salt spray test is often used. It can also help to determine the service life of that particular component.
Specimens are subjected to either a continuous or intermittent fine mist spray, which is made up of five per cent salt solution, to decide at which point they start to corrode.
This form of testing has been used for over 90 years to determine the degree of protection afforded by both inorganic and organic coatings on a metallic substrate.
The neutral salt spray test is the most common form of this method, with testing lasting for anything from just 8 hours up to 2500 hours, depending on the product and the specification. This test consists of atomising a salt solution into uniform droplets on specimens supported or suspended between 15 – 30 degrees from the vertical.
The salt spray test provides many benefits but one of the most interesting is that it is a multi material test which can be used not only for testing bare materials but also those which are painted or coated.
Apart from being able to test large samples, this method is also beneficial in that a standardised material is required, the costs are relatively limited and compared to the natural environment the test duration is short.
Salt spray testing, whilst simple to perform, needs careful control and the results seem to be immediately understandable to everyone. This also makes it a useful tool for marketing purposes, though the constraints of the testing procedure should be outlined in any marketing materials so as to avoid any misunderstanding or misinterpretation.
Want to find out more about salt spray testing, then visit the Rotech Labs site on how to choose the best salt spray test for your needs.