Although conventional salt-spray tests (e.g., ASTM B117) are very widely used in the coatings industry, it has long been noted that correlation of salt-spray data with outdoor exposure results can be quite poor.  The Moly-White Pigments Group has taken a pioneering role in the development and promotion of more reliable test methods for corrosion resistant coatings.

Improved Test Methods
Test Methods based on altering exposure to cyclic salt-spray (e.g. 'Prohesion') and UV-condensation (e.g., QUV) have been shown to offer the best available correlation with outdoor exposure testing due to increasing industry interest, these cyclic methods were recently adopted as an ASTM standard under the designation ASTM D5894, "Cyclic Salt-Fog/UV Exposure of Painted Metal".  Typical test conditions are outlined in Table 1.

Cyclic salt-fog/UV exposure tests are believed to offer better correlation with outdoor results due to the incorporation of:

• a more appropriate choice of electrolyte (composition and concentration)
• UV and condensation induced degradation
• periodic cycling of test conditions, including temperature and wet/dry cycles

The superior 'real-world' correlation of cyclic salt-fog/UV exposure tests versus conventional salt-spray tests was very dramatically demonstrated in two recent industry studies on accelerated test methods.  As outlined in Table 2. cyclic salt-fog/UV exposure tests were found to offer tremendously improved correlation with field data versus the use of conventional salt-spray and other new methods that have been suggested to the coatings industry.