Priming PE

I don't bother to prime PE, but simply paint it along with the rest of of the vehicle.  Since ModelMaster Olive Drab sticks perfectly well to bare PE, I would assume that any MM Gray enamel would work as well.

Wash it with detergent or Simple Green, rinse thoroughly, and etch lightly with vinegar, rinse, dry, and paint.

To etch, let stand in ordinary white vinegar for an hour.