Prepping High density polyethylene (HDPE) panels for epoxy and bedliner?


I am going to fabricate a set of door panels for my 66 GT350R clone out of a sheet of High density polyethylene (HDPE) panel that I boought from Menards. The plan is to cut and fit, then prep for a coat of Raptor Liner to add some texture and to match the rear seat delete panels in the back. Do I need to coat with adhesion promoter prior to SPI epoxy, or just scuff and spray with epoxy?
I think Barry wrote in the TDS to cut a small piece off and place it in water…if it floats then it promotes.
Hopefully you’ll get some expert advice
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AFAIK polyethylene requires adhesion promoter. To be sure cut a sliver off the backside, get a glass full of water and drop it in there. It should float which will tell you it needs promoter.
hdpe is extremely difficult to get paint to stick to even with adpro. this plastic is not going to be the best thing to use and a very poor choice if your trying to paint or put a coating on it. you would be much better off with abs or a styrene sheet. cheaper, easy to work with and takes coatings very well
I'm actually thinking about switching to 1/8" hardboard and coating it with epoxy and then bed liner to seal it and give it the texture I want.
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Why not just make them out of fiberglass. Use chopped strand fiberglass sheets and do 2 to 3 layers. Cut to fit your template and sand to get the desired texture. Then paint them .
Expanded PVC foam sheets is what custom interior/upholstery shops are using now for door panels and other panels on the interior.