Wood Putty vs. Wood Filler: Guide To Choosing Wisely

Whether you are working with wood for a DIY project or are looking to extend the life of a beloved wooden piece, your success depends on the minute differences between wood filler and wood putty. 

Your finished product would be incomplete without them.

With some unique uses and some commonalities, these two products can both help give your wood a strong and lasting finish – if you make the right choice!

Should I use wood filler or wood putty? The decision between filler and putty will depend on whether you need a hard, seamless finish or a flexible, durable hold. While fillers provide hardness and can be painted or stained, they are ineffective in improving strength. Putty remains flexible and is best for outdoor wood surfaces.

The ultimate difference between these two products is the final texture.  Here are some scenarios where this matters:

What should I use to freshen up my outdoor furniture? Wood putty is better because it can withstand fluctuating temperatures. It can help your wooden furniture last longer too.

What should I use to smooth out my homemade coffee table? Wood filler might be the superior choice here.

Especially if you are in the process of finishing it, filler blends in with the wood and finishes to be virtually invisible once sealed.

What should I use to fill in fastener holes in my project? Wood putty is the answer. The flexible, adhesive hold makes it the perfect solution when nails or screws are involved.

Just be sure to match the putty’s color to the finished wood.

What should I use to hide wood scratches? If you have not yet stained your wood, filler is a great way to cover scratches and match the color perfectly.

Though it may take some trial and error to match the stain to both elements, it’ll be hard to distinguish the two once complete.

What makes these so different? For two products with the same goal, it is a big surprise to discover the many differences between them.

Find out below why wood filler and wood putty differ in composition, texture, ideal wood type, and outcomes.

Wood Putty and Wood Filler Similarities & Differences

	Wood Putty	Wood Filler
Best Used For	Outdoor Wood	Porous Surfaces
Sandable	No	Yes
Paintable	No	Yes
Stainable	No	Yes
Cure Time	2-24 hrs.	10 min. – 2 hrs.
Hard When Cured	No	Yes
Can Be Used on Finished Wood	Yes	Yes
Can Be Used on Unfinished Wood	No	Yes

Wood Filler vs. Wood Putty

If you are facing the challenge of filling the final gaps and blemishes of a wood project, making the correct choice between filler and putty can influence the durability and lifespan of your beloved piece.

Here are the key differences between these products:

Wood Putty – What It Is & When to Use It

Wood putty is the ideal product when you are looking to touch up minor imperfections or fill small holes.

The distinguishing feature of wood putty is that it will cure to be slightly flexible and malleable. 

A key ingredient in wood putty is boiled linseed oil. This is just one reason why the product is so supple.

Being naturally adhesive and malleable, the putty can easily be spread across wooden surfaces with a putty knife to ensure that the final product is smooth and flat. 

Though this product cannot be mixed with stains or paints, wood putty comes in many shades to match the wood in your project. 

Due to the flexible nature of wood putty, it is an ideal material for outdoor wood and furniture that is vulnerable to shifting temperatures.

When wood is susceptible to shrinking and expanding with heat, adding wood putty can help the piece to resist those changes.

Though wood putty may take up to a full day to cure (depending on the surface area applied), the ability to hold its shape may increase the life of wood. 

Wood Filler – What It Is & When to Use It

Wood filler is ideal for wooden materials plagued with chips, gashes, or other imperfections.

The feature that sets wood filler apart is its incredible hardness that allows it to blend seamlessly with the wood around it.

There are different types of wood filler that can be applied to wood at different stages.

Water-based fillers can be used even after the wood has been stained, but these fillers should be used for indoor projects as they are less durable.

Solvent-based fillers have a thicker consistency. This stronger filler can be applied before the wood has been stained and may be used both indoors and outdoors.

All wood fillers require a seal to bond to the wood properly.

It is best to use wood filler on materials with a porous texture, such as ash, oak, and walnut. These types of wood have more gaps for the filler to sink in and bond sufficiently. 

Wood filler may be applied to the wood using a putty knife. This material will dry in as little as 10 minutes. As the filler dries, it may shrink slightly as it hardens.

It is best to apply more than necessary since the hardened filler can be sanded as you sand your wood. 

Once the filler is dry, it can be stained along with the wood. However, the filler may require extra attention to match the color exactly.

Are Wood Filler and Wood Putty Interchangeable?

Though these two products aim for similar results, they are not always interchangeable.

Choosing between filler or putty can depend on the type and status of the wood as well as the destination of the finished product.

Because of the differences in color between filler and putty, it is best to use filler with unfinished pieces and putty with finished ones.

Most fillers can be stained or painted along with your wood. Putty comes pre-colored and requires the user to match colors with their completed wood.

These products also differ in texture. Filler dries to be hard and brittle. Putty dries to be flexible and durable.

While wood filler can cure very quickly in a matter of minutes, wood putty might have you waiting an entire day to see the result.

Is Wood Filler as Strong as Wood?

Because wood filler consists of dust and other wood byproducts, it will dry to be very hard. However, the finished wood filler cannot improve the strength of the surrounding wood.

Why Does My Wood Filler Keep Cracking?

Wood fillers will dry to be hard and can even become brittle. If the wood is exposed to changing temperatures to cause expansion and contraction, the filler is susceptible to cracking.

Due to this risk, wood filler is best reserved for indoor projects.

Can I Paint Over Wood Putty?

Since wood putty does not ever fully harden, it is not recommended to paint it.

Can Wood Putty Be Sanded?

Since wood putty is applied flat with a putty knife after the wood is finished, it should not require sanding. Additionally, its soft texture would not be ideal for sanding.

Can I Put Wood Filler Over Caulk?

Since caulk can act as a sealant, it is best to use wood filler before using caulk.

How Do You Make Wood Filler Look Like Wood Grain?

One way to ensure that wood filler blends seamlessly with the surrounding wood is to mix in spare sawdust to the filler before it is applied.

This will help match the color and the appearance of the real wood.

Does Wood Putty Harden?

After the full time it takes for wood putty to cure, it will still maintain a flexible texture.

While not being fully hardened as the surrounding wood, this malleability can strengthen the wood by protecting it from weather changes. 

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Conclusion

Adding wood filler or wood putty to your project can be the final touch that creates a smooth and seamless finish on your project.

If you’re looking for strength and durability, putty can help patch holes and bolster fluctuating wood.

If you’re looking for a perfect match for an inside piece, filler can help create a flat and identical surface. 

These final additions can be the element that takes your project from scrap wood to a work of art.

Both wood filler and wood putty, when used correctly, can highlight the beauty and artistry of a piece.

Take care that you emphasize precision and color when working with these products. They will protect your wood for years to come.