Reaction between Paint Films and Zinc Surfaces

Abstract

The failure of paints to adhere properly to zinc or galvanized surfaces may be due to a combination of causes.It has been assumed that one of the possible causes was reaction between the decomposition products, formed in the drying of the paint film, and the zinc surface, producing compounds at the interface which destroyed adhesion.This study has shown definitely that reactions can take place between zinc and the oxidation products formed in the drying of oil or varnish type finishes, and that compounds formed as a result of this reaction are actually present on paint films which peel from galvanized surfaces. Zinc formate has been definitely identified as one of these compounds.

Pretreatment of Metal Surface for Painting

“…For example, the adhesion of most oil paints to a new hot-galvanized surface weakens after a short time so that the paint tends to peel. This is thought to be due to the formation of zinc formate on the interface between the pajnt and the zinc (23). If the galvanized surface is previously roughened by chemical or physical means, or if a considerable amount of zinc dust is added to the paint, adhesion is much improved.…”