Wood filler is a substance used to fill imperfections in wood, such as nail holes, cracks, and dents. It is typically made from a combination of wood fibers, resin, and a hardening agent. It can be applied with a putty knife or a brush, and it dries to a hard, smooth finish that can be sanded and stained to match the surrounding wood.
They contain real wood fibers in the form of a wood byproduct like sawdust or shavings that are suspended in a binder that dries to a hard finish with sufficient time. Even though they do dry hard, that hardness adds no structural strength to the wood it is applied on.
Wood fillers come untinted – no color other than the color of the wood from which the sawdust came. Once thoroughly dried, fillers can be sanded smooth and can be stained or painted. The fact they do dry hard distinguishes them from wood putty.
What Types of Wood Filler Are There?
Just as there are two main types of polyurethane and other wood finishing products, there are also two main types of filler: water-based and oil-based. Water-based filler is easier to clean up, but it takes longer to dry. Oil-based filler dries faster, but it is more difficult to clean up.
It’s a versatile product that can be used to repair a variety of wood surfaces. It is a quick and easy way to improve the appearance of your wood furniture, flooring, and other projects.
Here are some of the benefits of using wood filler:
- It can be used to repair a variety of wood imperfections, such as nail holes, cracks, and dents.
- It is easy to apply and sand.
- It is available in a variety of colors to match the surrounding wood.
- It is relatively inexpensive.
You can even make your own filler just with materials you likely have on hand in your shop – a little Elmer’s Glue and sawdust. Better still, if you have saved sawdust from the wood, the filler will be used on for nail holes, dents, gouges, or other mistakes during assembly.
Mix the two to a workable consistency and apply as you would any other type of filler.
There are tinted wood fillers, although there are not a lot of color choices, no more than a half-dozen or so wood colors. Depending on the color of the stain you have chosen, you may be able to come close with a tinted wood filler. But if your stain choice doesn’t match the 6 or so tinted fillers, close is the best you will get.
Plastic wood, such as DAP Plastic Wood, is an alternative to wood filler. It’s a high-quality latex-based filler that looks and acts like real wood. For filling a small hole, like a brad or nail hole, it can dry in as little as 15 minutes. It’s durable and strong and can be sanded, planed, cut, drilled into, nailed and screwed into, painted, and stained, all just like real wood.
Wood putty is a third option to fill holes in wood. Unlike filler, though, wood putty should be used only on finished wood, not raw wood. It comes tinted and can easily match the color of the wood stain already on the piece, so it isn’t necessary to worry about whether it will take stain.
How To Apply Wood Filler
Here are the steps on how to apply wood filler:
- Prepare the surface. Make sure the surface is clean and dry. If the surface is dirty or wet, it will not adhere properly.
- Mix it well. Follow the instructions on the product label.
- Apply it. Use a putty knife to apply the wood filler to the imperfection. Make sure to smooth out the wood filler so that it is flush with the surrounding wood.
- Allow it to dry. The drying time will vary depending on the type of wood filler you are using.
- Sand it. After it has sufficiently dried, use a fine-grit sandpaper to smooth it out.
- Apply a finish. If you are staining the wood, apply a pre-stain conditioner before staining. Once the stain is dry, apply a finish to protect the wood.
Here are some additional tips for applying wood filler:
- If you are filling a large hole, you may need to apply multiple coats of wood filler.
- If the filler is too thick, you can thin it with water.
- If the filler is too thin, it will not adhere properly.
- Be careful not to overfill the imperfection. Excess wood filler can be sanded off.
Problems With Wood Fillers Not Taking Stain Well
There are a few reasons why wood filler doesn’t take stain well.
- It is made from different materials than wood. Wood filler is typically made from a combination of epoxy, lacquer, or acrylic resins, and sometimes sawdust. These materials are different from the natural materials that make up wood, such as cellulose, hemicellulose, and lignin. As a result, wood filler reacts to stain differently than wood.
- It has a different surface texture than wood. Wood filler is typically smooth and even and without wood grain, while wood has a more uneven surface texture due to its grain. This difference in texture can make it difficult for stain to penetrate the filler evenly.
- It can absorb more stain than wood. Wood filler is typically more porous than wood. This means that it can absorb more stain than wood, which can lead to a darker color. Imperfections around the edges of the filler (microscopic, but there nonetheless) will pool the stain, and a darker ring can appear around the edge of the filler.
There are a few things you can do to improve the way wood filler takes stain.
Use a stainable filler.
There are a number of wood fillers on the market that are specifically designed to be stained. These fillers are made from materials that are more compatible with stain, and they are less likely to absorb too much stain. One such product is Minwax Stainable Wood Filler, and we’ve mentioned this in past writing about fillers.
Minwax Stainable Wood Filler is a decent product, but there is still the risk of rings and darker elements where stain has pooled.
Apply a pre-stain conditioner
A pre-stain conditioner can help to seal the surface of the filler and make it more receptive to stain.
Sand the filler smooth
Sanding the filler smooth will help to create a more even surface texture, which can make it easier for stain to penetrate evenly. To make your sanding easier, too, be sure to have wiped away all excess wood filler, and follow the drying time suggestion on the container.
Apply multiple coats of stain
Applying multiple coats of stain can help to build up the color and make it more uniform. You will have a better chance of a more uniform color if you use a dark stain instead of a light stain. A dark stain might lessen the chance of that dark ring around the filler edge we mentioned earlier, whereas a light stain will accentuate a darker ring.
A dark stain will also make any difference in color less noticeable overall, whereas a light stain will show differences more acutely.
By following these tips, you can improve the way wood filler takes stain and achieve a more finished look.
What Is Wood Conditioner?
We mentioned wood conditioner, a pre-stain conditioner, and just want to take a moment to expand just a little about it.
Wood conditioner is a clear liquid that is applied to wood before staining or painting. It helps to seal the wood and make it more receptive to the finish. Wood conditioner is especially helpful for softwoods, which can be very absorbent. It can also help to even out the grain of the wood, resulting in a more uniform finish.
There are two main types of wood conditioners: water-based and oil-based. Water-based wood conditioner is easier to clean up, but it takes longer to dry. Oil-based wood conditioner dries faster, but it is more difficult to clean up.
Here are some of the benefits of using wood conditioner:
- It helps to seal the wood and make it more receptive to the finish.
- It can help to even out the grain of the wood.
- It can help to prevent blotching and uneven staining.
- It can help to protect the wood from moisture and staining.
If you are staining or painting wood, it is a good idea to use wood conditioner. It is a quick and easy way to improve the finish of your wood projects and will not add significantly to the cost – only a little bit more of your time. The investment is worth it.
Is Painting Better Than Staining?
It depends, of course. What is the piece, and where will it go in your house? If painting is an option for your project, though, it might well serve you better than stain.
Paint coats the wood and filler, whereas stain changes the color of the wood and filler. There is no conflict between the color of the wood and the color of the filler because they both have the same coating.
If you’ve done a good job prepping the wood and sanded the filler smooth to its surface, a couple of coats of paint will have a good chance of hiding all filled holes in the wood. A more uniform color and application will present a more professional appearance, too.
Video Demo of Minwax Stainable Wood Filler
If you’ve never used a stainable wood filler, here’s a video demo of the MinWax product. It’s no harder to work with than other fillers, but its texture is a bit different.
Fillers of some sort are essential in woodworking to offer a professional appearance to our projects. Staining fillers can be problematic, yes, and there are filler options that might work better for you than others depending on the project, the wood, and the stain you have chosen.
Or, you can always choose paint, and if you’ve prepped well, that hole will disappear beneath a couple of coats.
