With plenty of low-cost commercial wood fillers and wood putties available, you might wonder why you would want to make your own DIY wood filler. After all, many off-the-shelf wood fillers are even tinted tomimic the colors of different woods. Still, many skilled woodworkers make their own wood fillers, and there is a reason.
Advantages to DIY Wood Filler
Do-it-yourself wood filler is often called cabinetmaker's putty, since fine carpenters often create their own filler to closely match a particular woodworking project. DIY wood fillers are generally made from fine wood dust mixed with a binding agent, because the very best way to match your wood's color is to use the wood itself.
Convenience is another reason you might want to make your own wood filler. If you run out of commercial wood filler while working on a project, you can whip up a small batch of your own in less than ten minutes.
DIY wood filler will closely match your project's wood, but it will not be exactly the same since the binding agent (glue) will be a different color. It works well for filling small holes and cracks but is not strong enough to bridge large holes, cracks, and gouges. As with any wood filler, your DIY filler will not be able to match the wood grain. Most wood glues are lightly brown-tinted, but if you can find white wood glue, it will create a better color match.
Tools and Supplies You Will Need
Mixing DIY wood filler is a messy process, so be sure to use latex gloves and a disposable mixing surface. Provided you do not have a latex allergy, latex gloves will fit tighter on your fingers than nitrile or vinyl gloves, making the mixing process easier.
Create the Sawdust
Unless you already have a pile of clean, fine sawdust, it will be necessary to make your own. An electric sander with fine-grit sandpaper will help you produce finer dust than that produced by cutting with a saw. Make sure that the dust matches the area you want to patch. For example don't use dust from a knotty area, which is usually darker than the rest of the wood.
- Wearing a particle mask, sand a piece of sample wood that matches the project material. A sander with a collection bag will simplify the collection of sawdust.
- Gather a pile of sawdust on a surface, and separate out any large particles or wood shavings that may happen to get mixed in. Clean obvious impurities from the dust, such as metal shavings.
Mix the Wood Filler
- While wearing latex gloves, gather a handful of fine sanding dust and place it on a mixing surface.
- Add wood glue to the mixture and stir with a craft stick, adding more glue until the mixture is a thick putty, roughly the texture of cookie dough. Avoid adding so much glue that the mixture becomes runny. Wood glue hardens relatively quickly, so don't dawdle—you have about ten minutes of total working time to prepare and apply the filler.
- Form the mixture into a workable dough that you can roll between your fingers. If the dough has already begun to stiffen, it will be difficult to apply to the work material. If this happens, start a new batch and slightly increase the amount of wood glue in the mixture. Once the proper texture is achieved, move immediately to the application of the filler to the work material.
Apply the Wood Filler
- Push the putty by hand into the gouge, scratch, or hole on the work material. Remove excess filler by hand.
- Working quickly, use your putty knife to flatten the wood filler and scrape away excess. Let the patch area dry completely.
- While still wearing gloves, immediately wash off the knife with warm water and soap. Glue-based wood filler is extremely difficult, if not impossible, to clean off tools once it is dry.
- Discard unused wood filler; it cannot be saved.
Finish the Project
After the wood filler has dried, sand the patch area very lightly with fine-grit sandpaper. It will not take much effort to sand the area smooth; avoid over-sanding, which will gouge the patch.
Wipe the patch area clean with a tack cloth, then paint or stain the wood, as desired.