Paint Failure, Steel Surface Quality and Accelerated Corrosion Testing

The large variation in salt spray performance of painted steels can be largely attributed to carbonaceous residues on steel surfaces. It has been shown that failure in the 240 hour salt spray test correlates strongly with high surface carbon. The adverse effect of surface carbon highlights the need for stringent control of steel surface cleanliness and for paint primers insensitive to alkaline undercutting. Corrosion tests have been developed which produce service-like failures more rapidly than are obtained with salt spray, by incorporating the use of freeze cycles, surface dust and high test temperature.