Does Wood Filler Harden? (Unlocking The Secrets)

Wood filler can be used to fix a damaged piece of wood. It helps the wood retain its structural integrity as it hardens. No matter how big or little the hole is, the wood filler can be used to fill it.

Though it’s possible to fix any mistakes made while working with wood filler, the process of hardening it is often misunderstood.

So, does wood filler harden or not? 

Yes. But with the help of a hardener. It can’t harden itself. It takes thirty to sixty minutes to get hard. Speeding up the hardening process is possible. To do so, clean the area, mix wood filler and hardener, apply a thin layer of sand to that area when dried, and finally, let it dry completely.

This was just a glimpse. There is a lot more to know about the hardening process. This article will describe them to you.

Does Wood Filler Harden Like Wood?

Wood filler does harden, to be sure. When exposed to the elements, the wood filler does not contract or expand as much as wood putty. And it hardens much more quickly than wood putty

Using wood filler to repair serious damage to indoor hardwood furniture is a fantastic idea because of the filler’s hardening properties.

What Is Wood Hardener?

Wood filler is a mixture of a sandable material and a hardening resin that is capable of soaking into and bonding with wood fibers. Lacquer, varnish, or glue mixed with wood dust (cellulose).

Don’t worry if you’re unsure about the hardener to use.

It may have been used by the ancients and is still used by woodworkers today. Various modern fillers are available on the market. Wood fillers harden as they cure, they can be sanded, and they can be stained, among other characteristics. 

Carpenters and woodworkers employ wood hardeners to reinforce the structural integrity of old, frail, rotten, or fractured wood. Chemicals known as wood hardeners serve to reinforce the structural integrity of the wood.

Wood fillers are also used to add weight to hollow materials.

When applied correctly, they seep into the wood and strengthen the fibers while also protecting them from other elements such as moisture and rot.

Can Wood Filler Harden Without Hardener?

Many carpenters, DIYers, and woodworkers use filler to fix or conceal flaws in their woodwork before finishing the project. Sawdust or wooden particulates are mixed with an adhesive chemical paste to form this substance. 

There is no way to harden the wood crack filler without using a hardener. The chemical reaction between the wood filler and the hardener is responsible for hardening. A catalyst, another name for the hardener, is also used in this context.

The hardener reacts with the wood filler in order for it to harden over time. Peroxide is used in the free radical polymerization of wood filler and hardener.

Without a hardener, the resin in wood filler acts as a barrier to hardening. The glue will eventually run out, and the wood filler will harden due to the presence of air oxygen.

However, it will take at least two years to complete this process. Because without a hardener, resin lasts a long time.

Even when the wood filler runs out, it doesn’t dry but rather sets. So, it’s important to add the hardener to the wood filler to make it stronger. Without the hardener, wood filler is useless.

Protecting the wooden surface from environmental factors such as temperature, moisture, and humidity is one way that wood hardener aids wood filler in strengthening the integrity of damaged wood.

It is possible to use wood crack filler in a variety of ways, depending on what you need. Different bases allow them to be used in a variety of different ways.

How Much Time Does Wood Filler Take To Harden?

Usually, wood filler hardens approximately 30 to 60 minutes after being applied. There are numerous factors that can affect how long it takes for wood filler to dry. In addition, the number of coats of wood filler you’ve used makes a difference.

You could have to wait up to 24 hours, depending on the circumstances. The more layers you put on, the longer it takes to finish. It may also differ depending on which hardener you are using.

To determine how long it will take for the wood filler to dry, look at the package of wood filler for specific drying and hardening times.

Wood Filler Product Drying Time
Minwax high-performance wood filler 2-6 hours
Elmer’s wood filler 2- 8 hours
Bondo wood filler 30- 60 minutes
Aqua coat wood filler 45-60 minutes

Types of Wood Filler

The different wood filler uses different formulas for different applications. When it comes to staining, some are better for painting, while others are better for staining rather than painting. 

There are several factors to consider when choosing a tool for a certain job. Before Working with wood fillers we need to know how to deal with them.

Water-Based Wood Fillers

This type of wood filler is made out of organic substances like cellulose, wood fiber, and minerals (e.g., gypsum). This type of wood filler dries easily; it may take approximately 15 minutes. It makes the whole process faster.

The best wood fillers have lower levels of VOCs (Volatile Organic Compounds). This means that they emit a less noxious odor when used.

Water-based wood fillers include two types of wood fillers:

1. Cellulose-Based Wood Filler

It is available as a dry powder that may be combined with a number of different solvents to generate a workable paste.

Water-based solvents or alcohol-based solvents can both be used, and both will work well in this application.

They’re easy to come by. Even your local hardware store will have them. To top it all off, the product lasts a long time before it needs to be changed. Because of this, they are used for staining in very thin layers.

2. Gypsum-Based Wood Fillers

This type of wood filler contains mineral powders. When dissolved in water, they produce a long-lasting solid. Thus, they do not fall apart as quickly as they dry. 

That’s not all; the wood fillers have a crystalline and transparent structure that allows them to blend in with the surrounding wood.

The drawback is that this form of wood filler has a short lifespan. The reason for this is that they are prone to stains as they age. Because of this, it is necessary to apply an additional coat of paint in order to achieve the desired effect.

Latex-Based Wood Filler

This type of wood filler is equally solvent-based. These are used to fill gaps or small holes in our wooden furniture, doors, or cabinets. It has the advantage of color variety. 

It comes in many colors and lets you choose the best one for you.

For applying it you will need a putty knife. When it is all dried up you will have to sand it for better smoothness and finish.

It also has some disadvantages. You will not get the highest structural strength with it. As a result, we recommend that you avoid using a nail or screw in that area after applying this product, as it could cause it to crack open again.

Epoxy Wood Filler

When you need the best structural strength, epoxy wood filler is the best choice. You can use it to fill in major holes or fissures. Using it can be messy at times. When using it, significant caution is required.

When it’s all dried up it is even stronger than the wood itself but it has a plastic-like appearance.

How to Make Wood Fillers Harden Faster?

There are a number of steps you can follow to speed up the drying time of wood filler.

Step 1: Cleaning Dirt, Stain, and Prepare the Hole

This is the most important part. If dirt and stains remain on the whole which you are filling it might slow down the drying process. 

Just grab a scraper and remove all the remaining small wood splinters. Any element like an extra splinter or Danish oil should be removed.

Remove the large ones as well. Wait for the wood to totally dry out before moving on.

Step 2: Proper Wood Filler/Hardener Mixing

A hardener is supposed to be with the wood filler, if it’s not then you will have to buy some because without it the wood filler won’t harden.

Do check the compatibility of the hardener with the wood filler. If it’s not compatible then the whole money is wasted.

Grab some wood and a putty knife. Using a putty knife, apply a weight of wood filler to a piece of wood and let it dry. This should take 3-4 minutes.

Put a bead of wood hardener across the width of the filler after you’ve applied the wood putty to your wood. Hardening wood putty is no different than this.

The mixture won’t harden properly if you don’t use enough hardener, and it will remain soft and squishy.

Scrape and knead the mixture with the putty knife until you can no longer see the weight of the wood hardener, then use the mixture to fill the hole.

Step 3: Applying and Layering Wood Filler

For best results apply the filler into thin layers. It helps the wood filler dry faster. The moisture content of thick wood filler layers is higher, so drying takes longer.

So, always use thin layers of 1/8-inch thick. There is enough room for the evaporation of moisture in thin layers.

But make sure the layers are not too thin. It might not fulfill the purpose of proper filling. So aim for the layer which is not too thick nor too thin.

While applying a layer over another one please make sure the previous layer was properly dried.

Step 4: Drying the Area

The wood filler must be allowed to dry completely by being kept warm and dry after application. Around 15-20 minutes should be enough time for this. Keep the wood in a warm environment to speed up the drying process.

Direct sunlight is recommended for speeding up the drying process.

Step 5: Proper Sanding

After the wood has dried completely, go over everything with sandpaper. Sanding also helps the filler to dry faster.

While you are sanding do make sure you are wearing a mask and doing it in a ventilated area. After that put it under direct sunlight to dry completely.


What wood filler dries hard?

Dab plastic wood dries hard. Both the water-based and solvent-based formulations of Plastic Wood Professional Wood Filler (shown here) are readily available. Neither is abrasive and can be used for priming and painting.

Are wood fillers strong?

Yes, wood filler is strong.  It dries quickly and solidly to a point. It may be sanded in as little as 30 minutes after hardening and can dry in as little as 10 to 15 minutes.

What is the difference between filler and putty?

Using wood filler, a damaged piece of wood can be repaired from the inside. It helps the wood retain its structural integrity as it hardens. On the other hand, putty contains chemicals that could damage the wood, that’s why applied only after the finishing has been completed.

Can I screw into wood filler?

It’s possible to screw into the wood filler. Epoxy-based wood fillers can be used to secure a screw. Wood fillers, on the other hand, can’t handle heavy loads. Therefore, the wood filler can only support small screws.

Does wood filler stain?

It’s difficult for wood filler to stain. Always test your staining procedure on scrap wood first to verify the wood filler looks precisely how you want it.


It means a lot to me that you read all the way through.I tried to give proper information on does wood filler harden. 

One more thing please wear a mask while working on wood-filling stuff.

Stay Safe, Good Luck!

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