Achieving A Paintable Surface right out of the Mold
Technique 1: Clean off piece with a high phosphorus soap such as Calgon automatic dishwasher detergent mixed with a little water. Then wipe down the piece with a small amount of solvent type cleaner (acetone). You must be sure to remove all residual release agent. (You can skip the Calgon and just use a solvent based cleaner if you prefer). Rub piece gently with steel wool to rough up the surface slightly. This will give you better adhesion for your primer. Prime with automotive primer and then paint with automotive paint or acrylic paint.
Technique 2: Clean molded piece as above. Then lightly sandblast the piece to abrade surface for better adhesion of paint. If using acrylic paint with the sandblasting method, no primer is needed.
Technique 3: Before you mold the piece, apply an in-mold primer (i.e. Pre-Coat 21 or 22).
Technique 4: Before you mold the piece, apply your release agent to the mold, then blow some ATH (Aluminum Trihydrate) powder over your release. Cast your piece as usual. When you demold the piece, wipe the surfaces of the piece with isopropyl alcohol or acetone, then paint. No primer should be required with this method.
* This technique is described in our Powder coating Technical Bulletin.