Causes

Poor intercoat adhesion, can result from surface contamination, sub-film corrosion and/or inadequate surface preparation prior to painting.  Non-ferrous metals (eg copper, zinc and aluminium) provide surfaces to which paint does not readily adhere unless appropriate surface preparation and priming is carried out. The cumulative build up of paint coatings will eventually highlight any areas of weakly adhering coatings.

Solution:

Remove all loose and defective coatings by scraping and/or the use of a proprietary paint/varnish remover. Remove any surface rust or corrosion salts and feather edges of sound paint with abrasive paper. Wash with hot water and liquid detergent solution to remove all oil/grease and any other contaminants. Rinse thoroughly with clean water and allow to dry. Lightly abrade and spot prime all bare metal with one coat of Crown Trade Universal Primer.