Causes

1. Contamination of surface by foreign matter prior to coating. Contaminants include water, wax, grease, oil, silicones, weld spatter, soap and mould release agents
2. Use of incorrect primer or topcoat system for substrate concerned
3. Insufficient preparation of substrate prior to coating
4. Re-coating of primer without allowing sufficient drying times, thus causing solvent entrapment
5. Use of cheap or insufficient thinners
6. Excessively thick paint films
7. Excessively dry or dusty spray technique

Prevention

1. Previously painted surfaces should be flatted and washed with copious amounts of clean water. After drying they should then be degreased thoroughly. Bare metal surfaces should be abraded and thoroughly degreased with the recommended HMG degreasing solvent
2. Do not guess the identity of the substrate! Seek advice on the correct primer/topcoat system
3. Thorougly abrade surface to be coated with appropriate grade of wed & dry/scotchbrite pad
4. Observe recommended flash-off and drying times with primers (consult technical data sheets)
5. Always use recommended solvent/thinners
6. Do not apply excessively thick coats
7. Always use recommended spraying pressures. Avoid excessive mists/dust coats, particularly of basecoat and etching primers

Rectification

The coating showing poor adhesion must be removed to a sound surface. Correct preparation of the surface must then be carried out.