Effects of residual white rust of inorganic zinc silicate primer on corrosion protection of epoxy-coated carbon steel

Inorganic zinc silicate primer is widely used in shipbuilding as a preconstruction primer (or shop primer) on steel plates; however, white rust of zinc is formed on inorganic-zinc-silicate-coated steel surfaces exposed to outdoor conditions such as rain and humidity. In this study, effects of residual white rust of inorganic zinc silicate primer on corrosion protection of epoxy-coated carbon steel were examined by water ballast simulation and condensation chamber tests. Pull-off adhesion, blistering, and cathodic disbondment tests were also performed for the same purpose. Test results clearly indicated that the residual white rust did not affect the corrosion protection when the steel surface was treated with light to heavy sweep blasting.