Paint Incompatibility: Loss of adhesion where many old coats of alkyd or oil-based paint receive a latex top coat. Possible Causes: Use of water-based latex paint over more than three or four coats of old alkyd or oil-based paint may cause the old paint to “lift off” the substrate. Remedy: Repaint using another coat of alkyd or oil-based paint. Or completely remove the existing paint and prepare the surface – cleaning, sanding and spot-priming where necessary – before repainting with a top quality latex exterior paint.