How To Apply A Clear Coat On Wood

Matt is a professional painter and freelance writer, sharing his knowledge, house-painting tips, and product reviews.

Why Use Grain Filler?

When preparing oak cabinets for paint, I use grain filler to smooth the surface. Without filler, the deep cracks in oak grain are difficult to prevent from showing through paint, especially if you're spraying instead of rolling.

In my experience, most of the grain filler I've used, including Aqua Coat, doesn't completely mask the grain pattern of oak in one coat, but one coat does fill the cracks, reducing the grain.

Aqua Coat is a clear, water-based gel that can be used on a number of wood surfaces, including kitchen cabinets, table tops, mantels and guitars. This product fills wood grain and helps seal it to help prevent tannin bleed in painted wood.

I have only used this product to prepare oak cabinets for primer and paint, so my review is solely based on my experience using it for that purpose.

Does Aqua Coat Wood Grain Filler Work?

I tried this product based on a recommendation from another painter. It's a water-based gel with a funky odor that smells like M&M's. It's messy to work with, but it's performed pretty good, so far, when prepping cabinets I painted. It doesn't completely mask the grain, but it fills the deep cracks that would otherwise show through the paint.

Applying this product on twenty-plus cabinet doors is very tedious, but worth the effort. I apply two to three coats, which fills and reduces the grain pretty well. If you want to only get rid of grainy cracks on the surface, one coat is not enough.

Completely leveling the grain with the surface would take several coats because this product is very thin and shrinks a little as it dries. In fairness though, I've yet to find grain filler that totally levels out grain with the surface in one coat.

As of this writing, this product is only available through Amazon. The pricing per quart of Aqua Coat is around $35 per quart, which is similar to other products I've used. Most of the cabinet jobs I've used it on required three to four quarts, depending on the number of coats being applied.

Applying Aqua Coat Grain Filler

The surface must be clean and dust-free. I wipe the surface with a tack cloth first to remove dust. The company itself suggests using a small squeegee, or putty knife, to apply the material, but an old credit card, or plastic taping knife, worked well for me.

A credit card makes it easy to work the gel into the corners. I don't recommend using a metal taping knife, which could scratch the surface of the wood. Wearing work gloves is a must. This stuff is messy.

You must apply this product in very thin coats, avoiding heavy build-up, otherwise, the sanding is difficult. Applying the material too heavily also results in a longer dry time.

The gel dries in a glossy film that must be sanded before top coating. You can sand the surface with a sanding sponge, or an orbital sander, using 220-grit sandpaper. If you apply a thin coat, sanding is easy. Depending on what you're using this product for, it could take three or more coats if you want to level out the grain more with the surface, but a couple of coats will get rid of the cracks and pores in the wood. When applied thin enough, the gel dries in about one hour.

When applying Aqua Coat, a little goes a long way. You can waste the material pretty easily by over-applying it. The company recommends waiting twenty-four hours before top coating with primer, paint or lacquer. I let the filler dry overnight before priming.

It's important to note that you cannot apply an oil-based polyurethane coating over this grain filler. The polyurethane won't bond well with the filler, resulting in peeling and failure. When using a sealer, the sealer must be wax-free as well. You can coat this product with oil-based primer, or shellac primer, like BIN.

Is Aqua Coat Good for Cabinet Painting?

I primarily use Aqua Coat for prepping oak cabinets and recommend it. There is a newer white paste version that's thicker and easier to work with than the gel version. The product makes the grainy cracks go away in two to three coats, but if you want to smooth out the grain on your oak cabinets even more, you'll need to apply additional coats. Most of my customers want to reduce the grain without visible cracks in the paint, so two to three coats is good enough for that purpose.

Most grain filler, at least the products I've tried, require more than one coat anyway if you're trying to reduce the grain and not see any cracks in the paint. The white paste version of this product is a nice improvement over the previous gel version. The white paste makes it easier to see the product in the grain during and after application.

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: Can you use Aqua Coat Clear Wood Grain Filler as a topcoat if you've already paint but want to hide grain?