Grain Filler for Painting Red Oak

How to fill open wood pores to get a smooth paint topcoat. July 17, 2008

Most of the time I prefer other people to do the finish coatings on my cabinetry, but last week I volunteered to do a small renovation for a local non-profit organization and did my own painting. I built the cabinetry out of whatever materials I had on hand in the shop, thinking that since it was getting painted, it wouldn't matter. Most of the casework was birch ply with a poplar face frame, but I ran short and made two of the doors out of red oak. When I primed it, the grain pores were still open. So I sanded, re-primed, and it was still noticeable. I sprayed the finish coat, sanded and recoated. While a little better at each turn, the pores were still noticeable to my eye when I was finished (client was thrilled). My question is, when painting an open-pored wood like RO, what can be done to fill the pores so as to get a smooth finish? And at what stage do you do this? Also, just for future reference, how does this work if doing stain-grade?

Forum Responses
(Finishing Forum)
From contributor J:
I would, after sanding and staining, spray 2 or 3 coats of Milesi SPA polyurethane sealer. That will fill the grain. Sand it down with either 220 or 150, then lacquer it.

From contributor B:
At this stage, you can simply give the surface a thin coat of latex wood filler and sand smooth with 320, then top coat.

From contributor M:
We use a paste grain filler from Chemcraft. You need to mix colour with it. Apply with a rag and as soon as it starts to flash off, wipe at a 45 degree angle across the grain with a piece of burlap to remove most of the filler and then finish with the grain with a clean rag to remove the rest. Let dry 24 hours and finish as usual. Normally we only grain fill tops for tables or desks.