Do I need to prime or paint MDF or plywood before applying epoxy?

No primer is needed. UltraClear Bar & Table Top Epoxy is an all-in-one system: the same product is brushed on as the seal coat and then poured on as the flood coat, so the wood does not need to be primed or coated with anything else first. The surface just needs to be dry and clean of any debris or contaminants.

If you want a solid base color under the epoxy, you can paint the MDF, plywood or Bondo'd particle board first. Use a latex or water-based paint. These dry quickly, and the epoxy can go over them in about 24 hours.

Avoid oil-based paint if you can. It takes a long time to fully dry, and if it has already been used you must apply three coats of oil-based polyurethane over it to seal it before the epoxy. Going straight over oil-based paint risks the epoxy not bonding properly, which can lead to delamination later.

We do not sell paint or a separate primer. If you would rather color the epoxy itself, add Pigmently Mica Powder Pigments or Liquid Dyes to the epoxy and read the color FAQ first: https://ultraclear.helpscoutdocs.com/article/80-epoxy-color-pigments