Wash-primers formulations for painting

Abstract

The objective of this research was to formulate two wash-primers containing “quebracho” tannin and the corresponding lanthanum “tannate” derivative. The primers were applied on rusted steel and on cold rolled steel surface as they stand after the production process. The primed panels were exposed to the humidity chamber to assess blistering and rusting degrees and adhesion by the cross cut test. The electrochemical evaluation was carried out by measuring the corrosion potential, the corrosion current density and the ionic resistance of the primed panels. Results showed that the primers had good adhesion on the panels with poor surface preparation. During the exposure to the humidity chamber the primers did not blister. Steel corrosion was constrained in the case of the primer containing “quebracho” tannin. Electrochemical tests showed that the wash-primers inhibited steel corrosion. As the primers do not possess barrier properties, corrosion inhibition is kinetic in nature by “quebracho” tannin and its derivative. No significant differences were found between the primer pigmented with “quebracho” tannin and that containing lanthanum “tannate”.