Method for improving the adhesion of a repair coating to a previously coated substrate

The invention provides a method for improving the adhesion of a repair coating to a coated substrate. It requires that at least one coating composition be applied to a substrate, the coating composition having (a) a film forming component with (i) a crosslinking component comprising one or more aminoplast resins, and (ii) one or more polymers having one or more functional groups which are reactive with the crosslinking component, (b) an adhesion improving additive comprising one or more compounds containing Sn(IV), (c) a catalyst for promoting a reaction between crosslinking agent (i) and one or more polymers (ii). The at least one coating composition is cured to provide a coated substrate and one or more repair coatings are applied to the coated substrate. In a preferred aspect of the invention, the one or more repair coatings applied are the same as the at least one coating composition. In a preferred aspect of the invention the at least one coating composition of the invention further comprises (d) an adhesion promoting component consisting of (i) an epoxy group containing component, and (ii) a monofunctional carboxy group component.