Filling Wood Grain

Mar 31

The majestic oak. It reminds us of beautiful hikes, tree houses as a kid, and…our kitchen cabinets. I’m not insulting your oak cabinets. Everyone is entitled to their own tastes, but many of us who grew up in the 80s and early 90s remember how EVERYTHING in the house used to be oak so we’re a little burnt out on it. Today, I’m going to show you a few ways to use that super grainy oak to your advantage or eliminate it entirely.

I have five red oak boards, three of which will be used for painting, and the remaining two we’ll apply a finish. Let’s start with the paint.

Prepping for Paint

If you want a smooth painted finish then you’ll have to fill in the wood grain prior to painting. Some people will try to use layers of primer and paint to fill in the grain. While that may work, I’m not a fan of the look of a lot of coats of paint. Instead, I’m going to show two different methods to fill in wood grain. One method is with wood filler. The other is with drywall mud. Yes, you heard me right, dry wall mud. Let’s start with the wood filler since that’s likely more well known.

Wood Filler

For today’s test, I’m using Timbermate wood filler. While it is not the cheapest wood filler you can buy, I think you get what you pay for. It dries quickly, it resists cracking, and if it dries out in the container, you can simply add some water to revitalize it. And that’s how we’re going to use it today.

Let’s start with putting a scoop of wood filler a dish. We’ll mix it with some water to make a runny paste. I like mine slightly runnier than peanut butter. I want it thin so it easily gets down in the pores of the wood. Since we’re painting this board, the color of the filler doesn’t matter to me other than I picked a light color since I’m painting it white. Now, using a piece of plastic or an old credit card, spread the wood filler across the surface of your board. Try to cover the whole thing. I covered my sample board and let it dry. Since it’s water based, it only took about a half hour or so. After it dried, I sanded the board with 120 grit and then with 180 grit sandpaper.

Drywall Mud

The other test board will get covered in joint compound. I used a trowel to work the mud into the grain. Because joint compound takes a long time to dry, I didn’t cake it on. I skimmed the board with the trowel, leaving the mud in the grain, but not a lot on the surface of the board. I let the sample board dry and then sanded it with 120 grit and then 180 grit.

Priming and Painting

Both sample boards were ready for primer and paint. I sanded an additional board that has no grain filler. This is our control board. It will only receive primer and paint so we can compare it to the other two boards. I applied one coat of primer to all three boards. After it was dry, I used a brush to apply one coat of semi gloss white paint.

The Results

This test is obviously not scientific. I did my best to apply equal amounts of grain filler, primer, and paint. That being said, there are variables. There are various types of wood filler, joint compound, primer, and paint. There are also various ways to apply all of the products. After looking over the three samples it was clear that the wood filler did the best job at completely concealing the grain. The sample with wood filler showed no wood grain. The sample that used the drywall mud looked really good, but when looking at the board from various angles it was clear that wood grain was still visible. It was faint, but there. This was possibly due to the joint compound shrinking as it dried. I’m confident that another coat of mud would have produced similar results as the wood filler.

Which method is best for you? Well, that’s up to you and your project. Wood filler costs much more than joint compound and took about the same level of effort to apply as the mud. It also didn’t shrink, took only one coat, and it dried super fast. If I were filling the grain in a piece of furniture, I’d probably reach for the wood filler. But if I was doing a super large project like an entire kitchen and time wasn’t an issue, I think drywall mud would be an excellent choice. Either method works great and produced much better results than the control board.

Popping the Grain

Instead of painting that oak, use the grain to your advantage. By highlighting the grain, the wood can look completely different. I took two red oak boards that I cut from the same long board, and I sanded them to 180 grit. Using the same method from the painting test, I applied a wood filler slurry on one of the boards. This time I used walnut tinted filler. I didn’t apply any filler to the other sample board so we can see a comparison. The one with the wood filler was sanded to 180 grit, leaving the filler in the grain of the wood. I applied two coats of shellac to both boards.

The Results

These look like two completely different boards! The one with the filler looks a bit more rustic and (to me at least) has more character. The one without the filler looks like that traditional, plain oak that we’ve seen a million times. The sample with the filler is also smooth. I conducted a writing test on both boards and, as one would assume, the grain filled board let me write smoothly while the regular board was difficult to write on without hitting bumps caused by the grain of the wood.

Here’s my takeaway on this test: it is completely subjective and depends on your taste. I personally like the board that highlights the grain much more than the control board. If you don’t, that’s cool. You do your thing. One factor to keep in mind is that the grain filling process may give you a leg up if you are staining. You can get some really cool effects by combining different color grain filler with different color stains.

The purpose in this test wasn’t to convince you to fill the grain of your oak boards. I wanted to introduce you to various ways that you can fill the grain of wood if you choose to do so, and show you the different ways in which filling the grain can impact the overall look of your project.

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Wood GrainFilling Wood GrainPainting Oak