Paint testing: A survey of some modern techniques Part 6: Corrosion and weather resistance

Abstract

Previous articles in this series have described some of the techniques that are used to characterise paint film properties. In many instances results from such tests are used predictively, that is they yield information on the likely performance of the coating during service. It is however, widely accepted that the most accurate way of determing performance is to actually subject the coating‐substrate combination to the service conditions it will meet in practice, or a close approximation to them. Suitability can then be assessed by periodic inspection and/or by taking measurements of some appropriate parameter which might be expected to change with time. A great many techniques have been developed and refined over the years that are intended to replicate service environments in some simplified and reproducible way; an indication of the range of test methods that can be employed to this end can be seen in a recent article by El‐Sawy. Many of these techniques are suitable for the laboratory and range from simple immersion tests in appropriate solutions through to exposure testing in controlled environment cabinets. Because of the problems of interpreting the results from laboratory simulation testing though, exposure of test panels in the natural environment is also widely practiced. This, the last article in this series, will consider some of the recent literature concerning environmental testing, with particular reference to techniques appropriate for assessing the weather, marine and corrosion resistance of coatings.