How to Use Wood Filler: A Step-by-Step Guide

If you like tackling home improvement projects, you've probably seen all sorts of imperfections on wood. Nail holes, cracks, chips, you name it—and it can be a little disheartening to find any of these marks on expensive furniture or even wood you'd like to repurpose.

Fortunately, using wood filler is a very simple and effective strategy to salvage or restore imperfect lumber. Learn how to use wood filler properly in this short, seven-step guide.

Types of Wood Fillers 

The type of wood filler you choose will depend on your project and its location. Some wood fillers work best for outdoor applications, while others will only work indoors. Water-based, oil-based, and epoxy-wood fillers are the best choice if you need to stain or paint the wood filler. Wood putty offers flexibility and avoids cracking for projects that may flex, expand, or contract.

Water-based wood filler:

• Indoor use

• Stainable and paintable

• Doesn’t hold up well to moisture

• Easy clean up with water

• Slower hardening time

Oil-based wood filler:

• Indoor and outdoor use

• Stainable and paintable

• Holds up well to moisture

• Clean up with acetone

• Faster hardening time

Epoxy-wood filler:

• Indoor and outdoor use

• Stainable and paintable

• Holds up well to moisture

• Clean up with acetone

• Must mix two components together

Wood putty:

• Indoor use

• Not stainable or paintable

• Doesn’t hold up well to moisture

• Easy clean up with water

• Best for small repair jobs

When Not to Use Wood Filler 

Wood filler is an amazing product that can help you fill in gaps and cracks, stop wood rot, and fix chewed-on wood, but there are some cases where wood filler isn’t the best choice. If you’re dealing with damaged wood, it may not be a question of when not to use wood filler but rather which wood filler not to use.

For instance, water-based wood filler isn’t a good choice for wood that comes into contact with moisture, so don’t use it on outdoor projects or in bathrooms. Choose an oil-based or epoxy-wood filler instead.

Both oil-based and water-based wood fillers dry hard and may crack if the wood flexes. For areas that see a lot of expansion and contraction, like floors, wood putty may be the better choice.

It’s always important to check the manufacturer’s instructions before choosing a wood filler because they’ll offer guidance for appropriate applications and tips.

Prepping to Use Wood Filler for Repairs or Projects

You can purchase a tub of wood filler for under $15, although you might need to pay a little extra if you need a certain color or finish.

Wood filling products are often designed to match popular stains and paint colors to make any repairs simple. If you kept the stain you used initially, look for a product that matches that color.

Take time to assess the wood you're trying to fix. Does it seem like wood filler will be enough to salvage it? If you're unsure, ask a local carpenter, especially if you're planning to use it on something like your floors. Depending on the job, a handyperson near you or a local furniture refinishing company might also be great resources.

How to Use Wood Filler

Wood filler can restore cracked, chipped, rotten, or chewed-on wood to its original state, but following the right steps is important. Choosing the right wood filler, properly preparing the wood, and waiting the proper amount of time before staining or painting go a long way toward completing a successful project.

1. Choose the Right Wood Filler

Solvent-based and water-based wood fillers are both stainable. However, keep in mind that there are other types of wood fillers that you can choose from, such as indoor wood and outdoor wood fillers.

Be sure to match the wood filler you need to the item or section of your home you're fixing.

“One time, we ordered a truckload of oak flooring, but the product we received was a low ‘utility grade’ product with large cracks and knot holes,” says Bob Tschudi, Expert Review Board Member and general contractor in Raleigh, NC. “We were about to sell it for salvage when our interior designer suggested that we install it, fill all the holes and cracks with wood filler, and then sand, stain and coat. The result was amazing and actually added value to the house.”

2. Sand Down the Parts You'll Be Repairing

If the wood you'll be working with is rough, splintered, or just not in the best shape, take some sandpaper to smooth out the areas that need wood filler. This step will help make the second half of the job easier, and sanding down rough edges is the best way to prepare the wood before you stain it.

3. Apply Wood Filler to the Holes or Cracks

Using a putty knife, apply wood filler to each crack or hole you intend to fill. Add more wood filler to each hole than it appears can reasonably be added; you will brush away much of it later.

Really work the wood filler in with a putty knife. Your goal is to jam as much wood filler into the crack or hole as possible to fill it up.

4. Rub the Wood Down Lightly With a Rag

Rub any excess wood filler away from the edges or surface with a cloth. It's okay if you don't get it all—it's just easier to remove while it’s wet.

5. Let the Wood Filler Dry

Always read labels, but wait at least two hours for your wood filler to bind and dry. Deeper holes or cracks (more than 2 inches) may need additional time or several applications. You may need to use wood filler in sections on holes larger than an inch—for example, half an inch at a time.

6. Sand Down the Edges

Use sandpaper to clear off any excess wood filler around the edges of the crack or hole. Having both regular and extra fine sandpaper may be a good idea here. You can really smooth out the edges and help your wood look brand new again.

7. Stain or Mix and Match Wood Filler, if Needed

Once it's dry and sanded, use stain or paint to make everything one uniform color.

If you accidentally use the wrong wood filler or plan to stain it once it's done, you might buy a wood filler crayon ($5 to $7 at hardware stores) that's slightly darker or lighter to help bring the colors together.

Note: When painting furniture, it's important to always do so in a well-ventilated area.

Helpful Tips for Using Wood Filler 

Using wood filler can make a damaged piece of furniture or flooring look new again, and these tips will help you do it:

• Choose the right wood filler for your project.

• Always prepare the surface by cleaning and sanding it smooth before applying wood filler. 

• If necessary, learn how to remove stain from wood to give yourself a fresh start.

• Wipe off excess wood filler while it’s still pliable to save some effort later.

• Wait for the filler to dry completely before sanding, painting, or staining it.

• Read the manufacturer’s instructions for tips on how to apply wood filler. 

• Choose water-based wood fillers for indoor projects and oil-based or epoxy-wood fillers for outdoor projects.

Wood Filler: DIY vs. Hiring a Pro

Using wood filler for most basic home improvement projects is simple and generally something many homeowners can tackle without a problem.

However, there are a few instances where hiring a furniture specialist might make sense:

• Wood is cracked or chipped significantly

• You can't find a stain or paint to match the wood

• You're afraid you might damage expensive furniture further

Consulting a handyperson or someone with wood repair knowledge can also help you avoid any costly mistakes.

“If you are trying to repair or match wood colors, it’s important to hire a pro who is passionate about finishes,” Tschudi says. “You want to find someone who has a passion for colors and textures and making the final result look as perfect as possible.”

Ben Kissam contributed to this piece.