Wood putty and wood filler may appear similar for first time users.

However, these closely related products function on wood surfaces with different degree of damage. c

ommon thing for both is repairing damaged wooden surfaces. In this post, the focus will be on wood putty vs wood filler.

Here’s what you need to know before we dive deeper into the discussion.

Wood putty and wood filler vary in their composition.

Putty consists of oil-based compounds and plastic chemicals, whereas the latter comprises fibers blended with wood particles.

Wood filler repairs the lumber from inside, as it hardens and maintains wood’s integrity, while the wood putty is ideal after finishing.

Distinguishing wood putty and wood filler is vital. It helps you avoid using them interchangeably and compromising your project’s quality.

In addition, read through this guide for more insights on these two formulas and how to handle them for maximum benefit.

What Is Wood Putty and When to Use It

Wood putty is denser than wood filler, and it is so supple that you have to apply it with a putty knife.

It is also similar to window glazing or plumber’s putty because it is a mixture of oil-based solvents and plastic.

The product does not harden and thus will not shrink or crack. Hence, you cannot sand or stain it.

Fortunately, some putty types have multiple colors to match various wood shades; therefore, staining is unnecessary.

Wood putty is suitable for repairing holes, nicks, and gouges on finished surfaces.

It also covers nail holes and, unlike a wood filler, is a perfect option for hiding scratches on tables.

Changes in humidity and temperature usually lead to wood expansion and contraction.

And outdoor lumber structures are more susceptible to them.

Luckily, wood putty comes in handy for these projects as it expands and contracts with the lumber.

Wood putty is ideal for fixing minor repairs and imperfections, including small blemishes, nail holes, and minor joint mismatches.

You can also use the product for flooring and interior woodworking. Therefore, you are at liberty to work on various projects.

What Is Wood Filler and When to Use It

Wood filler comprises a suspended sandable material in a resin solution.

The formula can soak into and bond with lumber fibers, allowing it to harden after curing.

In addition, the filler is sandable, and you can easily rub it, thanks to its porous nature.

The paste is available in a spreadable type that you can use for the grain of flat interior surfaces, like countertops and tabletops.

Also, you can spread it uniformly with a putty knife and sand it flat before adding a topcoat.

The filler comes in handy when you want to cover significant damages on indoor wooden structures.

In addition, since interior projects do not contract or expand dramatically, the product being rigid is not a disadvantage.

However, you may have difficulty matching the paste with a wood stain.

Thus, testing a small wood filler portion first is advisable before applying wood stain. This way, you can determine if the colors match.

Wood fillers fill scratches, nicks, and gouges in unfinished wood.

They also work for wood flooring and filling gaps between floorboards on hardwood floors.

In addition, you can use the filler to mold and shape damaged shelves, tabletop, or countertop edges.

Finally, we have two-part fillers that work for outdoor and indoor projects.

They resemble wood putty because of their non-porous, dense, and unstainable attributes. However, you can sand them for a smoother finish.

Wood Putty Vs Wood Filler

Wood putty and wood filler mean the same thing to most woodworkers, who use them interchangeably.

However, although they serve almost similar purposes, they are different products and ideal for varying wood filling applications.

In addition, knowing the difference between wood putty and filler is essential for any successful project.

It makes it easy to pick the most suitable product and facilitates the best outcome.

Significant differences between wood putty and wood filler include:

• Ingredients

The differences between wood filler and wood putty begin with the composition of each paste. Wood filler has wood byproducts suspended in a binder that help it harden during curing.

On the other hand, wood putty comprises oil-based and plastic compounds that remain flexible for longer.

There are liquid wood filler types that fill narrow cracks and slivers by penetrating the lumber fibers and binding them.

Also, remember that since the product hardens and does not remain flexible, it is not a prudent option for exterior repairs. 

In addition, the filler can crack as it dramatically expands and shrinks in response to significant humidity and temperature changes.

Therefore, only use it for damaged indoor projects.

The filler binds directly to the natural wood, relieving you from having to stain the project.

On the other hand, it is advisable only to use putty on finished lumber as it can ruin unfinished wood.  

Putty has oil-based compounds consisting of calcium carbonate, boiled linseed oil, and universal colorants that damage the wood.

So, it is best to stain the surface before applying the wood putty to create a barrier between the wood and the chemicals.

Wood putty takes a long duration to cure and set.

However, this period lengthens or shortens depending on the humidity and temperature levels, the product type, and the repair size.

Therefore, you may wait up to 72 hours for it to dry to the touch.

Also, remember that putty remains supple even after drying, making it ideal for exterior repair jobs.

• Painting and Staining

Most wood fillers are paintable and stainable and thus are not available in multiple hues.

On the other hand, wood putties are available in various wood colors since you apply them on stained surfaces.

In addition, the former features a unique composition, allowing it to blend with a wood stain in different concentration levels.

Typically, the best filler for stains should have a high natural wood particles amount level.

Otherwise, pastes with higher mineral concentration levels do not hold stains well and lead to a poor finish.

Oppositely, wood putty is not stainable. But it is available in multiple wood tones, so all you need to do is get a shade that best matches the surface.

In addition, exterior wood putty matches popular fence and deck stain colors for added convenience.

• Sandability

It is okay to sand wood filler as it hardens and becomes permanent, and thus you do not have to worry about ruining your work.

However, it is advisable to avoid sanding or smoothing wood putty because of its flexible texture.

• Consistency

Wood filler dries to deliver a hard surface. Thus, it is possible to apply it to large cracks, sand, and paint and forget about it.

In addition, although the paste does not replace significant repairs, it provides some structural support.

On the other hand, wood putty is flexible, just like clay. This pliability makes it suitable for stained and finished wood.

But refrain from sanding the surface because of the product’s softer texture.

• Indoor vs. Outdoor Applications

Wood filler hardens into a sandable surface that works well for interior projects.

However, outdoor projects will separate from the paste because the lumber contracts and expands with changing seasons.

In addition, water-based wood filler returns to its soft, flexible form when it comes in contact with moisture.

Therefore, it may compromise the integrity of your outdoor structure.

Conversely, the wood putty features a more flexible texture even after curing. It can shift with the lumber, potentially avoiding separation and cracks.

And as a result, you can use it for filling knots and gaps on hardwood floors.

Let us now check out some pros and cons of wood putty and wood filler to help make a better distinction.

Wood Putty

Here are the pros of wood putty:

• Adhesive Properties. Wood putty has adhesive attributes that work perfectly without a sealant. However, please note that this benefit only works with oil-based formulas.
• Cost-Effective. A small putty container lasts a long time, making it a budget-friendly filling agent. In addition, a few acetone drops will refresh and rehydrate the paste in case it dries.
• Best for Outdoor Furniture. Unlike wood filler, putty is more resistant to rain and sun effects. Therefore, it resists dramatic expansion and shrinkage, making it the perfect alternative for exterior furniture.

Cons

• Longer Drying Time. Most wood putty types need more drying time than wood fillers.

But the drawback with this attribute is that light-colored putty may accumulate dust and darken.

Wood Filler

Here are some of the advantages of wood filler:

• Available in Multiple Types. There are more wood filler types than wood putty, ranging from sustainable wood filler to epoxy, latex, and polyurethane. Thus, you are confident of finding an option that suits your project needs.
• Relatively Fast Drying. Wood filler starts to dry about ten minutes after application. And in most instances, you only need a maximum of 24 hours before resuming regular use.
• More Versatile. Wood filler is more versatile than putty because it is available in more types. In addition, there are countless things that you can use when working with indoor furniture.

Cons

• No Adhesive Properties. Wood fillers do not have adhesive attributes. Therefore, it is advisable to seal the product when finishing the workpiece.
• Not Flexible. The product does not expand with increasing temperature levels and will break when the wood contracts or expands. Hence, it is unsuitable for exterior furniture or products exposed to elements.

How to Apply Wood Putty

Applying wood putty is similar to working with wood filler. However, there are a few tweaks to make for a satisfactory result. Here are some tips for using wood putty.

• Choose the Correct Wood Putty. Some putty brands dry faster than others, and you’ll also want your colors to match. Therefore, evaluate your options based on your project needs and consider testing the product in an inconspicuous area.
• Prepare the Site. Use a clean rag to wipe away dust, dirt, and moisture. You do not want loose debris and contaminants around the site.
• Work the Putty Into the Site. Ensure that the problem area is overflowing with putty. If you are using a stick, first rub across the crack. Then, scrape off the excess product with a scraper tool or an old credit card.
• Allow the Wood Putty to Cure. Most putty does not harden. But, some brands will feature an initial curing phase and become less gooey.

Please note that applying wood putty entails pressing the product into the gouge or scratch using a putty knife.

Other application tools include a craft stick, your finger, or a cotton swab.

Lastly, conduct a quick test to determine that the wood putty is dry, and you can press your thumbnail’s end to the surface.

If you get dents, allow the material to dry for some more time.

How to Apply Wood Filler

The first step is to get the correct supplies for the job.

They include a putty knife, wood filler, rags, oscillating sander, shop vacuum, tack cloth, wood stain, mineral spirits, and sandpaper. Then, follow the procedure below.

• Mix the Wood Filler

Mix the wood filler in its container with a putty knife. The product can separate after it sits for a while.

So, blend it until you get a smooth, peanut-butter-like consistency with a uniform texture and color.

• Apply Wood Filler

Since petroleum-based wood filler hardens pretty fast, you should work quickly.

On the other hand, you can take your time with water-based formulas as they are creamy and stay wet for longer.

Firmly press the paste deep into the scratch or crack and remove the excess. But avoid gouging the knife or applicator into the patched area.

• Smooth With a Finger

Press the wood filler into the hole with your finger and wipe off the excess. Then, quickly wipe the filler with a dry cloth to remove it from your finger. 

In addition, it is okay to use water for water-based products or mineral spirits for petroleum-based products for an accurate result.

• Sand the Wood Filler Smooth

Let the filler sit for about thirty minutes to an hour, and then pick up your sander.

However, proper wood fillers dry so hard and may give you a challenging hand-sanding session. Thus, it is better to utilize an oscillating sander.

Start with medium-grit sandpaper and move slowly to fine 180-or 220-grit paper. Then, conclude by hand-sanding the surface with 220-grit sandpaper.

Also, please work in the wood grain direction to avoid leaving faint scratches on the surface.

• Wipe With a Tack Cloth

Sanding dust creates problems during finishing or staining.

The liquid mixes with the residue to produce a grainy and lumpy surface, the opposite of what you want from nicely sanded wood.

A tack cloth is often the best accessory for removing sanding dust as it does not introduce water into the material. Therefore, you are sure of avoiding more problems. 

• Finish the Wood

Once the surface is clean, the filled patch or crack is ready for stain or a protective coat.

In addition, staining the wood helps to equalize color differences between the surrounding lumber and the filler.

However, do not expect the wood filler to be entirely invisible because it absorbs stain differently than bare wood. Thus, the tone is seldom a perfect match.

Sometimes, you may still get a failed project even after following the correct application procedure.

For instance, if you get poor quality wood filler or overdo the product, it is inevitable to compromise.

Here’s a Video On How to Apply Wood Filler:

Tips for Easy Working With Wood Fillers and Putty

Here are some tips to provide an easy working time.

• Ensure the Wood Filler is in a Good Condition

Assess the condition of the filler if it has been on the shelf for a long duration.

Consider discarding the whole package if some parts of the formula are dry or do not mix well.

Also, a rancid smell indicates contamination and is a cue to throw away the wood filler.

• Avoid Overdoing the Filler

Usually, it is tempting to load up the putty knife with more filler with the hopes that you’ll sand off the excess.

But the formula hardens solid rock and can be a challenging task to sand it smooth.

In addition, the filler may become more rigid and stronger than the wood itself when working with softwoods.

Therefore, it is even more difficult to sand the surface.

The safest strategy is to be conservative with the product when applying it to the crack or joint.

Fortunately, you can always use more if it shrinks during drying.

• Remove Major Dust with Vacuum

A shop vacuum is the best appliance to remove massive dust amounts from the project. Then, use tack cloth for the fine dust film.

• Remove Fine Dust with Tack Cloth

A tack cloth is a wax-coated and sticky cheesecloth that removes fine dust from lumber surfaces before finishing.

However, pressing it too hard can deliver the opposite effect.

You could embed the lumber with the rag’s wax, necessitating another sanding round.

• Consider Pre-colored Wood Fillers

Seasoned woodworkers sometimes prefer to pre-color the wood filler before applying it.

In addition, the wood stain is easy to mix with wet filler before application. So, you work with a better blend and deliver a more consistent hue. 

However, this exercise takes some experimentation as the wood filler absorbs stain differently than natural wood.

For instance, it would be best to get a darker stain when tinting the filler. This way, you get a matching color for the overall project.

Also, consider using water-based stains for water-based wood fillers and solvent-based stains for petroleum-based fillers.

How Long After Using Wood Putty Can You Paint?

It is advisable to paint wood putty after it dries to the touch.

Therefore, consider painting after two to eight hours, depending on the putty application procedure and the existing weather conditions.

In some cases, the wood putty must dry overnight for a satisfactory result.

Also, remember that oil-based or water-based binders can dry differently because of their various components.

So, consider testing the filler with sandpaper to determine its drying time.

Can I Put Wood Filler Over Primer?

It is possible to apply wood filler over primer, but it is not an ideal situation.

The recommendation comes in handy when you see additional scratch marks after using your first paint or primer coat.

Reapply the filler over the first coat of primer or paint and wait for it to dry.

Then, sand the surface as you usually do and wipe off the dust with a tack cloth.

Frequently Asked Questions

• Does Wood Filler Stick to Painted Surfaces?

Wood filler does not stick properly to painted surfaces. The coating compromises the bond between the wood surface and the filler.

Thus, sanding the wood with 80-180 grit sandpaper and removing all the paint is advisable.

• Can I Use Putty Instead of Wood Filler?

The choice of the product to use depends on the project at hand.

Also, although the products work as a wood hole filler, they have varying limitations and uses.

Wood putty should only be on stained or finished surfaces.

It has harsh chemicals that can harm exposed wood. And as a result, wood putty is not suitable for interior furniture applications.

Nonetheless, putty is cost-effective and accommodates a tight budget. You can also have it for your outdoor work as it is sun and rain resistant.

On the other hand, wood filler is perfect for unfinished wood, meaning you can stain it later for added protection.

In addition, it is available in various colors and thus suitable for multiple surfaces.

Conclusion

Retailers and most woodworkers often fail to differentiate between wood putty and wood filler.

In addition, you cannot count on these people to help you determine the most suitable product for your work.

Therefore, let’s clear up the confusion with the discussion:

Wood Putty vs Wood Filler

Wood putty is best for repairing small holes and cracks on finished woodwork.

It has harsh chemicals that may cause damage to raw lumber and thus not fit for outdoor applications. 

On the other hand, wood fillers are ideal for unfinished wood as they are easy to sand and stain. So, you can use them to fix exterior furniture.