PPA 571 - Over-spraying with Thermoset Powders

Plascoat PPA571 can be successfully over-sprayed with thermosets such as polyesters, epoxy polyesters and epoxies. These materials will stick very well to PPA571 provided that the PPA571 has not been over-heated.

PPA 571 can be over-sprayed with polyester to give:

An almost infinite number of colours
High scratch resistance
Flexibility
Pinhole free coatings
High impact strength

It is best practice to apply the thermosets when the PPA571 is at a temperature of around 120°C (250°F) to 160°C (370°F). However, polyester powder can be applied onto cold coated parts. If the PPA571 is too hot the thermoset powder 'floats' on the surface of the PPA571 and a spotty finish is often obtained.

The spray gun should be set at 40kV or 10 μAmps (or on the 'overspray' setting).

Once the thermoset powder has been applied it should be cured using the normal curing schedule recommended by the suppliers.

Note: If the PPA571 is re-heated from cold then this can result in poorer adhesion between PPA571 and the thermoset overcoat. It is best to overspray with the thermoset powder after the PPA571 has been applied and has cooled to between 120 and 160°C (250 and 370°F).

15/02/2010

Technical Resources Area

PPA 571 - Over-spraying with Thermoset Powders