Matt is a professional painter and freelance writer, sharing his knowledge, house-painting tips, and product reviews.
Why Fill the Grain on Oak Cabinets?
Using grain filler on oak cabinets you're painting fills deep cracks and pores, reducing the natural pattern of the wood for a much smoother finish when painted.
In my experience, it's difficult to completely remove the intense pattern from the surface of oak without applying multiple coats of filler, but usually, one coat is enough to reduce it and remove the noticeable cracks that would otherwise show through the paint.
If you plan to prime your cabinets with a roller, without using filler first, the pressure from the roller forces primer into some of the cracks, filling them, but the deeper ones will remain, especially on large cabinet doors, which are usually the most grainy.
Grain filler is a must when spraying because the sprayer alone isn't forceful enough to fill in the cracks on oak all the way. Applying grain filler is tedious and messy, but if you don't want your painted cabinets to look grainy and rustic, the process is worth the effort.
Clean and Sand the Cabinets
I always clean and sand my cabinets first to expose the oak grain more so the filler covers the surface better without blockage from grease. Unless your cabinets are really greasy, good old Dawn dish soap works great for surface cleaning, using coarse cleaning pads. You can use de-greasing cleaner, or denatured alcohol too, which evaporates, leaving no residue on the surface.
The cleaning can be done after sanding, but I prefer to do the cleaning first to prevent chemicals from being absorbed into the open pores of sanded wood. After sanding, always wipe the doors with either a damp rag or a tack cloth.
My favorite sander for cabinets is the Makita random orbit sander. I use that sander to prep all of my decks and cabinets. The best sandpaper grit to prepare oak cabinets for grain filler is 100-grit. This grit removes the glossy lacquer coating from cabinets fast without causing damage. You can use a finer grit too, but it will take longer to sand.
Applying Grain Filler
Most grain filler is applied with a taping knife, trowel, brush, or a rag. When a taping knife is used for application, one made of plastic is best because using a metal knife can leave scratches on the surface that show through the paint. I've even used expired credit cards to apply wood filler, but a wide taping knife is faster for the paneled part of a cabinet door.
Skim coat the doors without leaving heavy edges, or globs in the corners. Sanding is a lot easier with a light, even coat. For narrow edges and intricate trim along recessed panels on cabinet doors, it's easier to apply the material with your finger. You can clear build-up from tight corners and edges with the sharp edge of a putty knife.
Some products, usually oil-based, can be applied over the grain with a rag and then buffed off the same way. The material sort of evaporates, leaving a white haze on the surface that comes off when you wipe it. I personally use water-based products. If you use an oil-based product, make sure the primer and paint you're using are compatible over it.
The number of coats to apply depends on the look you want to achieve. On my cabinet jobs, I usually apply one to two coats to get rid of the cracks and reduce the grain.
Best Wood Grain Filler for Oak Cabinets
Before I get to the products I've used successfully, I'll mention the ones I've used unsuccessfully. I tried Timbermate grain filler once, and it was a nightmare to work with, as well as Master Finishing Medium by Faux Masters. Timbermate was very difficult to sand and smelled absolutely horrible.
Master Finishing Medium is a grain filler that can be sprayed on, which is what attracted me to the product, since not having to knife the material onto the surface would be a huge time saver, but this product was a huge disappointment instead. When the filler dried, it left air bubbles in the grain that wouldn't go away after priming. I had to apply a skim coat, using another product, to hide the air bubble holes showing along the grain. I definitely don't recommend either of those products.
I've used Aqua Coat grain filler many times on oak cabinets with success. The filler is now available in a white paste, which works better than the clear gel version. It dries very hard. You have to be careful not to apply this product too thick otherwise it's difficult to sand. This product is messy to work with, but fills cracks in oak when used correctly. Like I mentioned at the beginning of this article, it's hard to totally remove visible grain from oak, but you can reduce it by applying two to three coats of this product.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Questions & Answers
Question: On a oak test drawer I have put on 4 thin coats of Aqua Coat - sanding lightly between each. Thereafter, I put on 1 coat of Bin shellac primer and stopped. I can still see about 80% of the grain, albeit I have only sprayed 1 coat of primer. Should I apply more Aqua before spraying a second coat of primer to minimize the grainy look?
Answer: Every grain filler I've used, including Aqua Coat, will fill most of the oak grain holes and cracks in one coat, but it won't hide the grain pattern, if that makes sense. Multiple coats of grain filler would have to be applied to make the grain pattern flush with the surface if that's what you're trying to do. What I do is apply one coat of grain filler, sand, and apply two coats of BIN primer. The BIN primer, combined with the grain filler, fills the grain really well to make the cracks go away. This reduces the grainy look so it doesn't look as much like painted oak, but if you want to make the surface totally smooth, with no traces of the oak pattern, multiple coats of filler will be necessary.
Question: Do you use oil based primer over Aqua Coat before spraying lacquer on cabinets?
Answer: I mostly use shellac primer, but I've used oil primer over the grain filler.
Question: What do you think about using a basic drydex spackle to fill in grain?
Answer: I've never used the product you mentioned, but I'd go with a wood grain filler over spackle. The wood grain filler I recommend in the article works great; I use it on all of my cabinet painting projects. But if you use, spackle to make sure the product can be used on wood. I would also make sure it dries hard enough for use on cabinets. Some spackle is meant for drywall and dries very soft. I'd also check the dry time.
© 2018 Matt G.