A Beginner’s Guide To Using Wood Filler: Tips and Tricks

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In woodworking, there are some givens that we expect and plan for as the project nears completion and the pieces are assembled.  Our nails, brads, and screws are handy, as are the drill and hammer.

The piece comes together well, but those nails, brads, and screws leave marks – holes that need to be filled.  We do want a professional appearance, and we want to be able to take pride in our work.

Of course, there are also the little accidents that occur along the way, the dents, dings, and scratches that occur when we get clumsy or careless. We also run into joints that don’t quite fit perfectly, and the result is gaps in wood, like the 45-degree corners that end up being something less.  Those need to be filled, too.

Fortunately, there are materials that are made to come to our rescue in such instances.  Wood fillers and wood putty are those materials, and although they are very different, they nonetheless serve the same purposes:  filling nail holes, covering screws, and generally filling holes in wood.

There are little tricks and creative workarounds we all come up with as we work more with wood over time.  Woodworkers are also happy to share that kind of creativity on bulletin boards and at the lumber yard or hardware store.  Working with wood fillers is no different.  We’d like to do the same for you.

What is Wood Filler?

Wood fillers serve the purpose their name implies – they fill holes in wood, no matter the cause of the hole. Wood fillers contain real wood fibers, usually a wood byproduct, something like sawdust or shavings that are suspended something to bind everything together like water or a petroleum-based substance.

Wood fillers dry hard, although they add no structural strength to the wood to which it is added.

Applied to your unfinished natural wood, and once they have thoroughly dried, they can be sanded flush with the surface of the surrounding wood, as well as stained or painted. They are easily applied either with your finger (for small holes) or with a putty knife, pushed into the hole being filled, and smoothed by the blade of the putty knife or your finger.

Wood filler is a versatile product that can be used for a variety of projects. It can be used to repair furniture, trim, and other wood surfaces. Wood filler can also be used to create a smooth finish on wood surfaces.

Here are some of the benefits of using a filler:

  • It is easy to apply.
  • It is sandable, stainable, and paintable.
  • It is available in a variety of colors, although limited in number.
  • It is relatively inexpensive.

It comes in a can or other similar container, as well as in tubes, and even comes in a crayon-like form.  The way in which it can be applied will depend, in part, on how it comes to you in these forms. 

For instance, Minwax Stainable Wood Filler comes in both a container and a tube for small jobs.  The tube makes application easy and direct.  Mohawk Fil-Stik filler, a tinted wax stick, comes in an almost crayon form and in many stain and wood colors, also making application easy and direct.  For larger containers, a putty knife is your best bet.

Types of Wood Filler

There are several different types of wood fillers available, and each one has its own properties and applications depending on several factors.

Some of the most common types of wood fillers include:

  • Water-based fillers are easy to apply and clean up after, and they are less likely to yellow over time. However, they can take longer to dry than other types of fillers. They tend to be crumbly in consistency, but because they are water-based (with additives, including a binder and real wood fiber), they can be smoothed with a little water. They clean up easily, again, because they are water-based and dry quickly. Some brands will dry in as little as 10 minutes and can be sanded in as little as 20 minutes.
  • Oil-based fillers are more durable than water-based fillers, and they dry faster. However, they can be more difficult to clean up, and they can yellow over time. They have an inherently smoother consistency than water-based and do not need anything to become more so. They will be of more protection to wood against moisture and humidity, again because they are petroleum-based.
  • Epoxy fillers are very durable and water-resistant, making them a good choice for outdoor projects. However, they can be more difficult to apply, and they require more time to dry.
  • Polyurethane fillers are similar to epoxy fillers in terms of durability and water resistance. However, they are easier to apply, and they dry faster.
  • Spackle is a type of drywall compound that can also be used as a filler. It is easy to apply, and it dries quickly. However, spackle is not as durable as those mentioned above and really is best suited for sealing cracks, filling holes, and covering seems on drywall.  

The best type of filler for you will depend on the specific project you are working on. Consider the size of the hole, the location of the hole, and the type of wood you are working with when choosing a wood filler.

For our purposes today, we are addressing the first two types of fillers: water-based and oil-based.

Can Wood Filler Be Stained?

Yes, wood filler can be stained. However, not all fillers are created equal. Some wood fillers are more stainable than others.

The best way to determine if a filler is stainable is to read the label. The label will usually state whether or not the filler is stainable. If the label does not state whether or not the filler is stainable, it is best to err on the side of caution and assume that it is not stainable.

If you are unsure whether or not a filler is stainable, you can always test it out on small pieces of wood scraps you have lying around in your shop. Apply it to the scrap wood and then stain it. If the filler takes the stain well, then you can use it on your project. If it does not take the stain well, then you will need to use a different type of wood filler.

Here are some tips for staining wood filler:

  • Use a high-quality stain. A good quality stain will help to ensure that the wood filler blends in with the surrounding wood.  If the color does not quite match to your satisfaction, you can always enhance the color with an additive – we speak to this in the next section. 
  • Apply the stain evenly. It is important to apply the stain evenly to the filler. This will help to ensure that it has a uniform color.  This is true, generally, when staining wood, and it applies equally to wood filler.  
  • Let the stain dry completely. It is important to let the stain dry completely before you apply a topcoat. This will help to ensure that the stain does not rub off.
  • Remember that wood filler has no grain. It’s simply a mixture of wood material and a binder with hardening additives. If the hole being filled is in the midst of some beautiful grain in the wood surrounding it, even if the stain took well, it will stand out as not matching the wood grain. The filler will not absorb the stain like the solid wood around the hole and look out of place in the grain. This is just a fact in woodworking, as frustrating as it may be.

Can You Add Color To Wood Filler?

Yes, you can add color to wood filler. There are a few different ways to do this.

  • Use a pre-tinted filler. Pre-tinted fillers are available in a variety of colors, so you can find one that matches the color of your wood. There are around 5-6 different wood colors available in pre-tinted filler.  However, depending on the choice of stain color you have chosen for the project, you might be able to come close if the chosen color is not among those half-dozen or so. If your choice matches one of those wood colors, you’re in luck. You do want the entire piece to look uniform in color.
  • Add color to a neutral-colored filler. You can add color to a neutral-colored filler by using a paint, stain, or dye. Simply mix the colorant with the filler until you get the desired color., whether a few drops of stain or dye blended in with the filler before application.
  • Use a wood stain to color the filler. Once the filler has dried, you can use a wood stain to color it. This is a good option if you want to match the color of the wood filler to the stain you are using on the wood.  To get the color you want on the filler, you might want to use a fine-tip paint brush and a stain color darker than the one used on the wood.  Remember that filler is only part wood fiber and will not take stain as real wood does. 

No matter which method you choose, be sure to test the color of the wood filler before you apply it to the wood. This will help you make sure that the color is what you want.

How Best To Apply Filler

Working with filler is not especially difficult.  There’s a hole, or dent, or ding, or crack that needs to be filled; the filler is soft and pliable and simply needs to be pushed into the space to be filled.  Here are some steps to follow, all of which are pretty common sense:

  1. Prepare the area. Clean the area around the damage with a damp cloth or tack cloth. If the damage is on a painted surface, sand the area lightly to create a rough surface for the wood filler to adhere to.  Remove all dust from the hole or area being filled, as filler will not adhere well to dust and will become loose in the hole.
  2. Mix the filler. Follow the instructions on the wood filler container.
  3. Apply the filler. Use a putty knife to apply the wood filler to the damaged area. Be sure to overfill the area slightly, as the wood filler will shrink as it dries.
  4. Smooth the filler. Use a damp cloth to smooth the wood filler. Be sure to work the wood filler into the surrounding wood grain.
  5. Allow the filler to dry. The drying time will vary depending on the type of wood filler you are using. Check the container label and follow the dry time recommendation.
  6. Sand the filler smooth and flush with the wood surface surrounding it. Once the wood filler is dry, sand it smooth with fine-grit sandpaper just as you would the wood.  If the area being filled is large, you might want to use an orbital sander, although with nail holes and such, hand sanding will work just fine.
  7. Finish the wood. Once the wood filler is sanded smooth, you can finish the wood with paint, stain, or varnish.

Additional Tips and Tricks For Applying The Filler

Here are some additional tips for applying wood filler:

  • Use a sharp putty knife to apply the wood filler. A dull putty knife will make it difficult to get a smooth finish.
  • If you are filling a large hole, you may need to apply multiple coats of wood filler. Allow each coat to dry completely before applying the next coat.
  • Water-based wood stain should be matched with a water-based filler; conversely, an oil-based stain should be matched with an oil-based filler.
  • If you are working with a water-based wood filler, be sure to work quickly. Water-based fillers dry quickly, so you will need to work fast to smooth it out before it dries.
  • If you are working with a petroleum-based wood filler, you can use a hair dryer to speed up the drying time.

Video Demo of Filler Crayons

You might be used to using a filler that comes in a tube or a can, but if you’ve never used a filler crayon before, you might want to consider the Mohawk Fil-Stick.  Watch this video to see it in action.

It’s inevitable in woodworking that you will use a filler at some point unless you are using old-world woodworking techniques that do not require nails, screws, brads, or other mechanical accessories to hold wood together.

It’s a pretty straightforward process, and the results can be great if you follow these tips and read the instructions on the containers.  That professional appearance is right around the corner for you as you complete your project.

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