STANDARD DEGREES OF RUSTING

Last month we published the conclusions of the Joint Technical Panel of the British Iron and Steel Research Association in their third interim report, “Painting of Structural Steelwork.” In their investigation it was necessary to establish some sort of scale of degrees of rusting of specimens. The rusting of the steel base of the test panel is obviously the most important criterion of failure. The photographs on this page show examples of the first five degrees of the rusting scale, up to 2%. The Panel is of the opinion that under practical conditions it is desirable to repaint steel where from 0.2 to 0.5% of rusting has occurred and in the tests inspection of any particular surface is discontinued after the presence of 2% of rust on it has been established. These photographs are not magnified.