Polyurethane parts can be successfully painted, but it is important that the surface is correctly prepared.

Check that the surface of the part does not have an oily feel to it; this is indicative of an incorrect resin/hardener mix, and will prohibit good adhesion; remake the part with the correct ratio.

Do not use a silicone release agent; this may mix with the resin and prohibit binding of the primer.

Allow the part to fully cure for at least 24 hours after moulding.

Thoroughly clean the part with an automotive grease and silicone wax remover, such as acetone.

Sand, using 240 grit paper, or sand-blast the surface of the part to etch the surface and give a ‘key‘.

Apply a thin polyurethane primer coat.

If indicated in the paint instructions, etch the painted surface.

Finish with a thin polyurethane top coat. Thick coats will take a long time to dry.