Full Fill Finishes on Open-Grained Wood

Several approaches to grain filling with Oak, Mahogany, and similar open-grained species. September 30, 2009

I need to finish some red oak cabinet doors with conversion varnish. What product should I use to full fill this kind of grain, without spraying several coats?

Forum Responses
(Finishing Forum)
From contributor C:
A polyester filler/sealer would be fairly easy, but don't expect anything to completely fill in one coat. There is a reason why full filled finishes are expensive. Hood Products has a spray nitro based filler which can be used under CV. There are a few options but all are time consuming.

From contributor R:
Try this. Lay down a couple coats of NC lacquer. Make a pad of cheesecloth with cotton inside. Put on your rubber gloves, saturate the pad with the NC lacquer and wipe your doors. You'll get the hang of it pretty quick, as to how wet your pad should be.
This is the last detail we do after an install. It also works over polyurethane, but not under.

From contributor T:
I'm currently producing a glass-like finish on African mahogany (open grain and open pore). I finally feel like I have tamed the beast. This is my new finish schedule.

1. Sand to 150 grit.
2. Wiping stain.
3. Three heavy coats (back to back) with MLC Level Sealer with 5% retarder thinner and left to cure overnight.
4. Sand aggressively with 240 grit until almost sanding through stain.
5. One, two or three heavy coats of Level according to each piece and just how grainy or porous.
6. Sand aggressively with 320 grit.
7. Topcoat twice with Duravar (back to back with a little scuff sanding in between).

I'm certain this schedule would work for oak as well.

From contributor J:
I use the paste wood filler from Sherwin Williams. I use gilsonite to tint the natural color but have also used different wood stain colors. I usually add color first then thin with paint thinner - should be looking for a consistency a little thinner than latex. Wipe directly on bare wood or apply a dye stain underneath depending on what you are trying to achieve. Donít apply too heavy but make sure it coats evenly; you can wipe off any excess. Let it dry 5 minutes or so until it starts to flash or look hazy. Lightly rub in a circular motion with burlap, which will pick up excess filler and help to work it into the grain. Try to work across the grain and not with it so that you donít rub the filler out of the grain. Have something like a toothbrush and toothpick to clean out any corners or detailed areas. Use a clean cotton rag as the last step to buff 'em out or clean off any excess material. Let them dry overnight and seal them up and go on with your normal finishing schedule.

Try some sample boards first, and donít try to do too many at once. You can always add more or less thinner depending on your temperature. You should be able to achieve a grain filled finish even on oak without having to use multiple coats of finish.