Reply by Matt Przybylski

I’ve had good results with priming the MDF using Zinsser BIN and then used General Finishes Enduro Var Poly that was tinted white as the top coat. It came out great (look at my projects, well, the only one :)

As Jim said, I sprayed it through my Earlex 5500 (both the primer and the poly).

-- Matt, Illinois, http://www.reintroducing.com