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First thing I did was sand the surface to 220 and cleaned off all the dust, then I mixed pore filler as directed: one part stain (I used colonial oak) and two parts filler. Most wood fillers need to be thinned to effectively get into the grain. I spread the filler over the entire top taking special care to get it into all the open pores working both with and across the grain. It’s best to work in small sections; the filler won’t leave overlap marks. Chris Minick in Fine Woodworking recommends, “Immediately after you've filled the grain (while the wood is wet), remove all the excess by scraping the surface at a 45° angle” (Minick 58). Then use a coarse rag to rub down the piece; the more the material you can remove equals less sanding. When the filler was completely cured (approximately 24 hours, but it can take a couple of days), I sanded from 150 up to 220, and then I put on my wipe-on poly blend (one part BLO, one part Mineral spirits, one part polyurethane- http://www.froggybuilder.com/index.php/projects/tips-techniques?start=16) with a cotton cloth.
Many of the sources I reviewed on this topic recommend using dewaxed shellac over the surface prior to using the wood filler and even in some cases after the wood filler prior to using a poly finish. It helps fill any little sink-holes after the filler shrinks (Minick 59). I tried using shellac in different orders on test pieces and found I liked the look better without the shellac, but it’s worth trying it out on some test boards before getting started on your final project.
At first, I was disappointed and didn’t feel like it had done what it was supposed to do–create a smooth top surface, but after I started varnishing the legs and the stretchers (no pore filler), I began to see the difference. After several coats of varnish, I could really see the effect—the top was very smooth.
For woods like cherry or maple the pores are so tight there’s no need for a pore filler, but woods like oak, mahogany, ash and even walnut the grain is very open. In some cases that might be a look you are trying to achieve, but if it is a smooth top you’re looking for, then a pore filler is required. It is a lot of work and messy, but the look is worth it.
Works Cited
“Finishing Room: Understanding Grain Fillers.” Woodsmith, Vol 30/No. 179. 2008, pp. 46-47.
Minick, Chris A. “Fill the Grain for a Glass-Smooth Finish.” Fine Woodworking, Sept/Oct. 1994, pp. 57-59.