Deterioration of paint systems applied on zinc substrates contaminated with soluble salts

The presence of soluble salts at the metal/paint interface is one of the ma in reasons that cause the premature deterioration of the painted metallic s tructures. This is specially important in the case of zinc substrates due t o the increasing amount of galvanised structures that are painted after wea thering (duplex system: galvanising + paint). Nevertheless, most of the stu dies to quantify the tolerable levels of soluble salts for different organi c coatings have been carried out with steel substrates. In this paper, the behaviour of some organic coatings appl led over pure zi nc contaminated with different levels of chlorides and sulphates is analyse d. Tests were conducted in the atmosphere as well as in the accelerated hum idity condensation cabinet. (C) 2001 Elsevier Science B.V. All rights reser ved.