Grain filling: What, why and how?
Red oak, hickory and ash are the most common species with “open grain.” While beautiful in their own right, they don’t take a finish evenly. No matter how much you sand, that bumpy texture will show in the finish. That texture can be attractive, but if you want a perfectly smooth finish, you’ll have to fill the grain. I usually fill the grain on tabletops and musical instruments.
MY FAVORITE FILLER
I’ve tried many grain filler products, but the only product I use now isn’t even a grain filler; it’s marketed as a water-based wood putty. Timbermate is made from wood flour and available in many species. It’ll accept stains, dyes and finishes just like the wood around it. It ages the same as wood, which makes me confident that my project will look good the day I complete it as well as years down the line.
1 MIX IT BY HAND
I start with two big scoops of Timbermate wood putty in a plastic food container. Wearing nitrile gloves, I slowly add water and mix it with my fingers. This takes time; mix until those last little clumps are dissolved.
2 SPREAD IT OUT!
When the slurry is the consistency of yogurt, I scoop it up with my hands and spread it on the wood. Just like I do when I stain, I’ll rub in circles and across the grain, working the filler into the pores of the wood.
3 GET THE SPOTS YOU MISSED WITH A SECOND COAT
Applying a second coat produces the best results; it covers little spots that were missed. I’ll even start the second coat before the first one is completely dry so the slurry remaining in my container doesn’t dry out.
4 SAND LIGHTLY!
I like to wait a day before sanding so the moisture has a chance to evaporate. I’ve achieved the best results using a random orbital sander that has effective dust collection, and variable speed so I can slow it down. I start with 80-grit paper and stop at 220.
TIP: I use only Festool sanders because they have the best dust collection of any random orbital sander on the market. More important, the complete absence of vibration means my hand and wrist won’t hurt after hours of use.
5 SEAL WITH SHELLAC
Shellac is very versatile! Because it’s compatible with all finishes, it can be used as a barrier between water- and oil-based stains and topcoats. I use thinned shellac as a prestain conditioner. I’ll also use it after grain filling to even out the absorption rate of the filler and wood, so the stain or topcoat lies down evenly. In addition, shellac can be used alone as a stunning topcoat, but that’s for another article (or three).