Filling Wood Grain for Perfect Finishing
Want to achieve a finish that not only looks like glass, but feels that way too? Try filling the grain first.
McKinney, Texas, woodworker Jim Kull, has been restoring furniture, building antique replications, and doing custom work full-time since he took early retirement over a decade ago. "It's something that I always wanted to do, but I wasn't expecting to set up shop until I was 62," Jim offers. "Today, I love restoration, and that includes wood finishing. So, when we wanted to get filled in on filling wood grain, we turned to Jim.
"If you want a glasslike finish, such as on a desk or a tabletop, you have to fill the grain-actually the wood pores in the grain," says Jim. "Oak is the best example. You can see an oak piece with either filled grain that has a smooth, reflective finish or with unfilled grain and a semi-rough look. The difference in texture is like glass versus fabric."
Yet, as with most anything, there's more to filling than smoothness, according to Jim. "Filling is more a matter of preference for the look you want or an effect that you are trying to achieve. Because in addition to finish texture, you can either accent the grain or subdue it-making it striking or bland."
There are essentially four ways to fill the pores of a coarse-grained wood like oak, walnut, and mahogany. And from Jim's experience, none of them prove easy.
"You can fill the pores with your finish material, whether it's varnish, lacquer, or water-base," he explains. "It just takes repeated coats with sanding in between. This won't accentuate the grain any more than it is naturally. Secondly, you can use a prepared water-based filler right out of the can. It takes stain, so you can highlight the pores, but it also has distinct disadvantages-like drying too quickly-that make it difficult to use. I don't bother with it."
That leaves two options: an oil slurry and commercial oil-based paste filler. Jim prefers the oil slurry, so we asked him to go through that process first.