It is not uncommon for woodworkers and homeowners to confuse wood putty for wood filler. It is understandable because both compounds are used to repair holes or gaps in wood by filling or covering them up.
However, wood putty and wood filler are two distinct compounds. Failure to distinguish one from the other leads to using the wrong product for the job, and the future impact on the wood would be detrimental.
So, what is the difference between wood putty vs wood filler? The difference between wood putty and wood filler is in the composition, making them suitable for different applications. While wood putty is mean to cover up blemishes in the wood such as scratches and nicks, wood filler is meant to fill in cracks, holes, and other larger imperfections.
If you’ve been making this innocent mistake of using the two terms interchangeably all along, here is an opportunity to learn more. In this post, we give you an overview of wood putty vs. wood filler.
The Differences Between Wood Putty And Wood Filler
In the course of woodworking, you’ll stumble upon tons of wood imperfections. Some naturally occur in the timber like knots, and others are caused by wear and tear, for example, from aging furniture.
However, most often, it is from inaccurate measurements, making erroneous holes, etc. But at the end of the day, you want a perfectly finished product.
That perfection can only be achieved by covering these faults and making them look less noticeable, if not fully camouflaged. This is where wood putty and wood filler come in.
What Are Wood Putty And Wood Filler?
Wood putty and wood filler are compounds used to patch up blemishes in the wood. It can be anything from nail holes to cracks, small gaps, dents, or scratches.
They are pliable and really get in there to fill up the space and cover the blemish. The finished patch then mimics wood, making the surface appear even and flawless.
As a result, many woodworkers, seasoned and newbies alike, confuse them for one and the same thing but they are, in fact, different products. Using wood putty in place of wood filler and vice versa can adversely affect the wood in the future. It can cause more damage to the wood by exacerbating the flaws you were trying to cover.
Unfortunately, this interchangeable use of the terms extends to some manufacturers as well. They will label their products as wood putty when it is wood filler and vice versa.
Therefore, you have to be keen to ensure you are purchasing exactly what you want. This would, of course, be impossible if you don’t know how to distinguish them yourself. Here are a few key differences between wood putty and wood filler.
1. Composition
The ingredients in wood putty and wood filler make the key difference between the two. The fact that they are both pliable in consistency makes it easy to think that they contain the same ingredients, but they do not.
Wood putty is made from petrochemicals. It contains polymers often in an oil base. For this reason, wood putty is at times referred to as plastic wood.
Colorants and calcium carbonate are also common ingredients in wood putty.
On the other hand, wood filler consists of by-products of wood such as sawdust and wood fibers combined with a binder, often in a water base. The binder could be latex, epoxy, or polyurethane.
2. Consistency
Being oil-based, wood putty has a smooth consistency. It feels like soft clay and is so easy to pack into holes. You can use a putty knife or even your fingers to dab some of it and get it in there effortlessly.
Wood filler is also spreadable but usually kind of grainy or tough, due to the wood fibers in it. Being water-based, it is smooth but not as soft as wood putty.
If you try to rub wood filler in between your thumb and index finger, it may crumble. Mixing in a bit of water, however, significantly improves the texture, making it smoother and easier to apply.
3. Usage
Both wood filler and wood putty play an integral role in the coverage of imperfections on wood, but there are defining aspects in their usage.
Wood putty is recommended for patching up blemishes on finished wood. That means you should apply wood putty to wood that has already been stained or varnished but before the finishing coat.
The reason why wood putty is used on finished wood only is because it contains chemicals that can be harmful to open wood in the long run.
They have damaging effects should they penetrate deep within the wood. That is why wood putty is restricted for use on already finished wood. Finished wood is not porous; the chemicals in the putty cannot seep in.
Wood filler, on the other hand, is ideal for the covering of holes, cracks, and other imperfections on unfinished wood. Because wood filler is made up of natural wood particles in a binder that does not contain any harsh chemicals, it is ok for it to come into contact with raw wood.
You can also use wood filler on finished wood then follow it up with the same finish as the rest of the wood. However, it would be best if you never used wood putty on raw wood.
4. Drying
Wood filler typically dries much faster than wood putty. Generally within 20 minutes, but some brands will dry in less than 10 minutes. The rapid drying process is attributed to the absence of chemicals. Once dry, wood filler becomes a rock-solid mass.
Most wood fillers will shrink when dry. Consequently, if there was any air trapped beneath it, the wood filler would sink, resulting in an uneven surface once again.
You can always add another layer of wood filler to top it off, but that’s double the trouble.
A better way around this is to ensure you put a little excess filler to the hole or crack the very first time. Once it dries and shrinks or sinks, it will be at the same level as the wood or slightly above, which you can sand down.
Wood putty, on the other hand, dries pretty slowly. It takes a few hours, sometimes an entire day, depending on the brand.
Therefore, it has a longer work time, and you can manipulate it for a while without any problems and even clean up excess easily. The putty can be evened out by wiping off any excess or scraping with a putty knife, scraper, or old credit card.
Sometimes the putty is combined with a hardener to accelerate the drying time and harden it a bit more. But we suggest leaving this to the expert woodworkers, as you might not be sure how the hardener will react with the chemicals in the putty.
Wood putty retains a small amount of stretch even after the total curing time. Its chemical composition has everything to do with the slow drying as well as the flexibility. As mentioned earlier, wood putty is made using plastics which give it these attributes.
5. Finishing
Since wood putty goes on already finished wood, it is available in a host of tints to match the color of the stain or varnish on the wood. You’ll have no trouble finding a uniform color for camouflage. You can even mix two different colored wood putties to get a new color that is closer to the tone you are looking for.
One tip for choosing a wood putty color is to go a shade lighter than the actual stain. Because it takes an extended time to dry, wood putty tends to get darker with time as it dries.
Most wood fillers are the natural color of wood. The color variety is, however, minimal because it is primarily applied to wood.
Therefore, there is no point in having different color options since the entire wooden structure will be varnished, stained, or painted anyway, and the wood filler will take up the new color.
Wood filler, unlike wood putty, can be stained and painted very well. It also mixes readily with dyes.
Notwithstanding, you have to pick a shade that is closest to the color of the wood. If there is a major difference between the shade of the wood and filler, the repair might be obvious unless you go for a full coverage finish like paint.
As for staining, you might end up with a mottled appearance if you do not experiment enough with a waste piece of wood. Wood filler takes stains differently from wood, so you must adjust the ratio accordingly to achieve an even tone.
By now, you should be able to make a clear distinction between wood filler and wood putty, having seen each product for what it is. And the next thing on your mind probably is, when do I use wood filler or wood putty?
We are getting to that shortly, but first, let’s quickly recap the differences between wood putty and wood filler.
| Wood Putty | Wood Filler | |
| Composition | Plastic chemicals in an oil base, colorants, and calcium carbonate | Wood fibers and water-based adhesive/binder like latex, polyurethane, or epoxy |
| Application | Applied on finished wood to touch up imperfections | Applied on raw wood to patch up imperfections before the wood is finished |
| Drying | It takes a few hours to a day to harden but maintains a degree of flexibility | It hardens in minutes and becomes rock solid |
| Colors | Available in a broad color spectrum | Natural wood color |
| Texture | Refined smoothness and pliable like wet clay | Grainy smoothness and spreadable |
| Finish | It doesn’t paint/stain well | Takes paints, stains, and dyes well when finishing the wood after application |
When To Use Wood Filler
By looking into the characteristics of wood filler, you can tell what it can and cannot be used for. For starters, it is absolutely safe for unfinished wood. So if you’d like to mask any blemishes on wood prior to finishing it, you know what to go for.
It also hardens enough to maintain the wood’s structural integrity. In addition, it contains actual wood fibers.
Therefore wood filler is ideal for both minor and larger or deeper blemishes. It is especially good for when time is of essence as it dries rapidly.
Unfortunately, wood filler is not durable when exposed to outdoor elements. When the temperatures rise and fall, wood shifts from warping to shrinking, and all that causes wood filler to crack due to its rigidity.
It is also a water-based product and can be dissolved by water and revert to its smooth consistency. For those reasons, it is best reserved for indoor applications.
Please note that the majority of wood fillers are water-based, but not all. A few are solvent-based. Solvent-based wood fillers can actually survive in outdoor conditions if you’d like to go that way. However, they are not the best for raw wood.
Some great uses for wood filler include:
- Masking knots and other natural flaws of wood like small cracks or gouges.
- Covering the dents left behind from driving in nails and screws.
- An alternative for edge banding on plywood if you are tired of it peeling every time.
- Filling gaps between two pieces of wood like the joint on picture frames. As long as the gap is no more than ⅜ of an inch.
When To Use Putty
Moving on to wood putty, we already know it is chemical-based and a big no for unfinished wood. So, for any fixes after staining or varnishing wood, you’ll reach out for wood putty.
Not just for a newly finished wooden item but even while repairing an old, finished piece of furniture or other items.
Woodworkers would generally opt for wood putty for tiny fixes. It is even evident in the packaging, as some brands have it in sticks where you just rub it across a scratch or little crack, and you are done.
Another instance where you’d reach for wood putty is outdoor applications. Wood putty is very durable in the exterior environment, unlike wood filler. If you recall, we did mention that it stays flexible even after drying. For that reason, it is unaffected by temperature changes.
When the wood outside contracts and expands due to temperature changes, it adapts to the shift and expands and contracts accordingly. Furthermore, wood putty is not water-soluble. It is waterproof and unaffected by moisture, so it will not be leached by rain.
Another fantastic use of wood putty is on floor repairs. Because of its flexing ability, it will not crack under pressure from the weight of feet as people walk by. To use wood putty effectively, you must have ample time. It is not a quick-fix kind of filler because it dries at a snail’s pace compared to wood filler.
In a nutshell, if the defect is minor, on finished wood or outdoors, choose putty. If it is large, on unfinished wood, or indoors, opt for filler.
That’s all there is on wood putty vs. wood filler. And hopefully, you’ll be using the right product for the right task next time. You can only tell the difference using this information by going through the ingredients listed on the product when making a purchase.
Both are very handy, and neither is better than the other. So if you are a prudent woodworker or homeowner, we suggest getting one of each.
It is better to buy more filler than putty, as you’ll need to use a lot of the product to fix more extensive problems. And when tightly sealed and properly stored, they have a long shelf life.
Up Next: What Is Drillable Wood Filler? – Does It Work?
