Wood filler is handy but can be useless if it hardens and gets stuck in the tube. Luckily, it’s relatively simple to rehydrate and soften.
To remove wood filler that won’t come out of the tube, use acetone or water to rehydrate it, then slowly work the liquid through to soften the filler. A tube of wood filler that won’t budge means the filler has hardened, so softening it to get it out is typically the best option.
Read more about why wood filler hardens, how to soften and get it out of the tube, and how to keep the filler from hardening in the future.
Types of Wood Fillers
There are several kinds of wood filler:
The two most common kinds are water-based and solvent-based. You can tell the difference between the two by opening them up and smelling them. Solvent-based wood filler has a chemical smell that water-based filler doesn’t.
Both kinds can harden if stored for long periods of time, the same way paint and varnish do. When keeping these products, oxidation is the enemy, as it causes them to coagulate, harden, and eventually become brittle and unusable.
What To Do When Wood Filler Won’t Come Out of the Tube
Keeping the filler’s container properly sealed is the most vital preventive step to take.
There are easy ways to fix or avoid this issue altogether.
- Identify which kind of filler you have. The procedures for water-based and solvent-based filler are slightly different — water-based will soften if you add water; solvent-based requires acetone to soften.
- Pour the water or acetone on the filler’s surface. Leave it to soak in for a couple of minutes until the surface is soft enough to poke holes in.
- Make holes for the solution to flow into. With the surface soft, you can begin poking holes in the tube to give the solution access to all of the filler from top to bottom. Give the filler time to soak and soften.
- Mix the filler into a paste. This is the correct consistency for the filler and shows that it has been properly rehydrated.
Sometimes, wood filler contains a hardening agent that allows it to harden on its own. Most of the time, it requires you to apply a hardening agent to it after the job is done. However, exposure to oxygen causes wood filler to harden independently.
Mia Secret Nail Polish Remover is a cost-effective, fast-working acetone solution that will soften a solvent-based wood filler easily. It dries quickly and leaves no oily residue behind.
The below video is a straightforward example of how wood filler works in action, as well as the process of preparing your wood before applying the filler.
Why Does Wood Filler Harden in the Tube?
Atmospheric oxygen oxidizes the wood filler, causing it to harden, even without the presence of a hardening agent.
Wood filler contains a small amount of water or other liquid that keeps it soft and pliable. When the filler is exposed to oxygen for extended periods, the moisture evaporates, causing the filler to shrink and harden.
Wood filler could lose moisture because:
- The lid isn’t fully sealed, exposing minute gaps.
- The tube has been damaged or punctured in some way.
- You’re storing it incorrectly.
Correct storage is vital in keeping your DIY equipment up to scratch for years. This is especially true for household chemicals and oxygen-sensitive solutions like wood filler.
How To Correctly Store Wood Filler
Properly storing wood filler is vital to preserve it and keep it malleable. It can take several years for wood filler in a container to harden completely if it’s not sealed correctly, but it’s a situation you want to avoid altogether, not delay.
- Ensure the tube is sealed. After every use, ensure the lid is tightly secured and no air can penetrate the filler. A helpful trick would be to place plastic wrap under the cap to create an extra sealant barrier.
- Store filler in a cool, dry place. If the tube of filler overheats, it can cause damage to the tube or evaporate the moisture from the filler. Both of these would severely dehydrate the filler.
- Keep it away from sharp objects. Store wood filler tubes away from anything sharp or heavy that could pierce or damage it. An easy option is to keep it in a sealed plastic container or jar.
- Store away from chemicals. Ensure there aren’t any chemicals close to the wood filler that could damage the tube and degrade, dissolve, or alter the wood filler.
What Happens When Wood Filler Becomes Brittle?
If you’ve ever worked with air dry clay, you know that exposure to air turns it completely solid and “cures” it fairly quickly. The final product is entirely dehydrated and can’t be rehydrated for reuse.
The same concept applies to wood filler. Once it’s dried all the way through, it’s impossible to soften it and use it in a project.
It’s unlikely that wood filler will completely dry if stored and sealed correctly. If you’ve done everything right and your wood filler still appears to have hardened, don’t throw it away; try to soften it using one of the methods listed here.
You won’t be able to tell if the filler is brittle unless you test it. Employ a hydration method according to what kind of wood filler you have; if it softens the filler, you can still use it for a good while.
If the softening solution doesn’t loosen the filler up at all, then it’s almost certainly because the filler has totally dried out. There’s nothing to be done to save it in this case other than getting a new tube of wood filler.
That said, you also don’t need to spend a lot of money on professional-grade wood filler, especially for smaller projects.
Different Types of Wood Fillers
Wood fillers are a byproduct of wood, like wood dust and sawdust, suspended in a solution such as petroleum or solvent. These are applied to holes and cracks in wood and dry rock-solid for a long-lasting cover-up.
Water-based fillers are quite crumbly in texture, which can make trying to rehydrate them tricky. They’re typically made with cellulose or gypsum. It’s simple to thin out and clean up.
Solvent-based filler is smoother and is known to be more durable, and can withstand the elements better than water-based. It tends to be more expensive than water-based fillers and takes longer to dry.
Wood filler is available in a range of packaging options:
- Tubs or tins
Tubs are an excellent choice for bigger projects, but tubes are perfect for versatile use and easy transportation. They also take longer to dry out in the event of an oxygen leak.
Elmer’s E887Q Stainable Wood Filler is ideal for interior and exterior use. The white finish is easy to paint and stain, and the tube is easily resealable for continued use over multiple projects.
Wood Filler Alternatives
Wood filler is the recommended product for DIY projects because of its superior quality and long-lasting results, but it certainly isn’t the only option out there. DIY wood filler is an easy and cost-effective alternative.
To make an easy DIY wood filler mix the following materials:
- PVA glue. This is an accessible, cheap, and effective base and is well-suited for indoor and outdoor use.
- Sawdust. Your sawdust should be a powdery consistency or as fine as it can get. This is crucial to making the mixture into a smooth, spreadable paste.
Mixing these together creates a smooth paste that resembles acrylic paint or wet clay: easy to spread but thick and quick-drying. You can add some coloring agent to the paste to match it to the wood you’re using or use sawdust from that same wood as an organic coloring agent.
You can always paint over the wood later, in which case the color of the filler doesn’t have much of an impact.
Before painting, don’t forget to sand your wood down for the smoothest possible finish and to ensure the DIY filler doesn’t leave any rough or bumpy textures that break the otherwise smooth wooden surface.
If sanding is too much of a hassle, you may prefer to power wash the surface instead of sanding it. Check out my complete guide on which one is a better option. [Can You Power Wash Instead of Sanding? 3 Things to Know]
Wait approximately 30 minutes to an hour for the glue solution to dry completely. The exact waiting time varies depending on the hole’s size and how much glue was used.
The following video illustrates how simple it is to make this PVA-sawdust paste and how easy it is to apply.
Stubborn wood filler is inconvenient, but the solutions are incredibly straightforward and cost nearly nothing to implement. If you have persistent issues with hardening wood filler, a simple alternative is a DIY mixture of PVA glue and sawdust.
Consider the scale and budget of your project. If your project is large-scale, you should stick to professional-grade wood filler. If your project is reasonably small, you can easily get away with a homebrew alternative.