Q.
I have heard several people speak highly of polyester primer. Does it have any advantage for MDF doors?
What equipment is required to spray it, and what is the degree of difficulty for application?
Is it available for small- to medium-sized operations?
A.
On MDF, I have guys laying down only two coats and they can sand everything to perfection.
While curing, this material converts to almost 100 percent solids because its solvent (styrene monomer) becomes a solid. Once cured, there's no shrinkback to speak of, and it can be topcoated with any product you want.
It sprays best with cup or gravity-feed guns. Only mix what you can spray in approximately 15 to 20 minutes, because you don't want this catalyzed product to "kick" in the cup. Don't let it scare you, though -- it's not as bad as it used to be.
Bob Niemeyer, forum moderator
Comment from contributor A:
I have been spraying polyester primer exclusively for about 10 years. It is my primer of choice. I manufacture MDF painted doors and would not use any other product. There are many on the market. The end product depends on your top coat. My company built our outstanding reputation on the quality of the polyester primer.
