5 Common DIY Wood Filler Problems When Using It (The Truth)

Many DIYers will come across a circumstance in which they must fix holes or fissures in the wood. Many people choose wood filler as their first option. However, the wood filler has a cost.
As a result, many people are now making their own wood filler by mixing wood glue with sawdust. However, this isn’t always the best option, and there are some DIY wood filler problems to be aware of:

  • You will have to deal with shrinkage.
  • It’s difficult to get a smooth finish.
  • Finishing the homemade wood filler is far from good.
  • You will never get the same strength.
  • Making your own wood filler is a messy and time-consuming task.

In this article, we’ll take a closer look at these DIY wood filler problems, how to avoid them, and what alternatives there are to homemade wood filler. This will help you figure out which option is best for you and the project you are working on.

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The difference between wood filler and wood putty

Before you read on, it is very important to know the difference between wood filler and wood putty. Many people hardly know the difference, but it is critical to know what you are talking about and also to be able to interpret the rest of this article correctly.

In short, Wood Filler can be used to fill cracks in the bare wood. This can then be covered with a top layer such as paint or stain.
Wood filler will begin to dry out and harden after a few minutes. Then it can be sanded and painted, after which you can no longer see the wood filler.

Wood putty, on the other hand, can be used to fill gaps in wood that are already covered with a topcoat.
Wood putty is soft and malleable and hardens only slightly. Because it can no longer be treated with stain or paint afterward, you will have to use wood putty with matching colors.

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Why use a DIY wood filler?

As I mentioned in the introduction, some people build their homemade wood filler in order to save money over buying professional wood filler.

They’ll make a paste out of sawdust and wood glue to cover the hollow or gap in the wood.

Another reason they do it is to avoid having to use wood putty and mix different colors to get a match with the wood. They will rather fill the gap in the wood with the sanding dust from the wood itself, resulting in a color match.

Let me be clear: neither of these arguments for making DIY wood filler is incorrect. When I don’t have matching colors or when I’m out of stock and need wood filler or wood putty immediately, I use it as an alternative myself.

However, there are too many DIY wood filler problems when using it, so I still prefer to use a professional wood filler. I will discuss the most common DIY wood filler problems below.

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The DIY Wood Filler Problems People Face When Using It

The DIY wood filler problems I discuss here are based on my own experiences but are also experienced by many other woodworkers I know. When I ask them about it, the same problems keep coming back. Perhaps you have already experienced them subconsciously, and you will be able to confirm this.

Problem #1: You will have to deal with shrinkage.

When making wood glue, the manufacturer will add water. This is done not just to make the glue liquid, but also to extend its shelf life.
When applying wood glue, evaporation causes the wood glue to penetrate and adhere to the wood.
This implies that the area filled by water during the application of homemade wood filler will vanish, and the DIY wood filler will shrink.

You might add a second layer or raise the first layer and sand after curing as a remedy, however, this would not cure the problem of shrinkage.
If you can see how the top has shrunk, you may be sure that the inside has shrunk as well. Perhaps much less, but the possibility exists.

After applying a two-thinner coat, there is also a larger chance that it may fall off when sanding.

So if you should choose to use DIY wood filler, it is good to keep this in mind.

Problem #2: It’s difficult to get a smooth finish.

It’s hard to find homogeneous particles from sawdust while making DIY wood filler. When you look for how to produce wood filler on the internet, you’ll frequently come across the suggestion to utilize sanding dust from the vacuum cleaner bag. This is correct somehow because that’s where the best sanding dust can be found.

However, you must be aware that bigger particles will be present as well. A dust collector does not differentiate between large and fine dust; it just sucks up anything that comes its way.

So, unlike a professional wood filler, a paste of sanding dust and wood glue would never produce a homogenous mass. The smoothness of the paste will be determined by the quantity of coarser components present.

Later, when the DIY wood filler is cured, and you sand, the risk that bigger particles will be drawn out of the DIY wood filler will rise, and you may not have a smooth surface in the end. Because of this, on the surface of the sanded homemade wood filler, you’ll see that there are little pores. The texture of the DIY wood filler will not be the same as the wood and will appear different since it is rougher.

This, in addition to the shrinking, is one of the biggest drawbacks of the DIY wood filler for me and many others with whom I’ve discussed it.

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Problem #3: Finishing the homemade wood filler is far from good.

This problem will be the natural next step if you’ve read the previous DIY wood filler problems.
Microscopic holes will form when the handmade wood filler shrinks. As a result, the density of the wood filler will differ from that of the wood. Whatever finish you use will penetrate the DIY wood filler deeper and faster than it will penetrate the wood. As a result, color variations are possible.

You’ll also notice a permanent difference after applying a finisher owing to the textural difference between the handmade wood filler and the wood. The texture of professional wood fillers is smoother, making it easier to hide after staining or painting.

Problem #4: You will never get the same strength.

Two of the preceding DIY wood filler problems, shrinkage and uneven grain size of the sawdust, may produce this problem.
The resulting holes and fractures will make the DIY wood filler weaker than a professional wood filler due to shrinking.

Professional wood fillers use particles of the same fraction, which means they will bond better with one another. The bonding will be weaker with bigger and softer sanding dust particles.

Although this isn’t a significant danger, it’s worth addressing when discussing the most typical DIY wood filler problems.

Problem #5: Making your own wood filler is a messy and time-consuming task.

If you have already made DIY wood filler yourself, you will understand what I mean by this. Mixing can be a messy job that requires some cleanup afterward.
So it is not only much cleaner when you use a professional wood filler, but it is also faster.
In times when every minute is precious, this is certainly not a negligible DIY wood filler drawback.

The alternatives to using homemade wood filler.

This is the point where you can make a choice.
If the DIY wood filler problems are not an obstacle for you or the projects you are working on, you can continue to use homemade wood filler. I am sure that for some of my projects I will continue to do so.

Are the DIY wood filler problems really a stumbling block for your projects, or have you become more aware of the disadvantages of homemade wood filler after reading this article, then you should start using professional wood filler.

This is also the product in which I have the most faith and with which I can confidently complete a project.

You won’t have to worry about the drawbacks of using a handmade wood filler if you use a solid wood filler.
But keep this in mind: not all cracks are the same and need the same filler. To understand this topic better, it’s a good idea to read my article, How To Fill Cracks In Wood (4 Creative & Easy Ways). This article will give you better insight and will help you find the type of filler you need for your project.

If you’re looking for a wood filler, I can recommend the Rubio Monocoat Wood Filler Quick from Rubio Monocoat.
It is a wood filler that is available in three different colors: light, medium, and dark.
The wood filler of Rubio Monocoat has fast curing and is completely shrink-free. This wood filler is easy to sand after which it can be easily stained.

5 Common DIY Wood Filler Problems When Using It - Rubio Monocoat wood filler - collors
5 Common DIY Wood Filler Problems When Using ItRubio Monocoat wood filler colors

The Rubio Monocoat Wood Filler Quick can only be used indoors and can be stored for up to 12 months.

Processing this wood filler is very easy:

Mix 5 portions of Rubio Monocoat Wood Filler Quick with 2 portions of water.
The mixture is best used within 35 minutes of mixing and is sandable after approximately 2 hours.

If you want more details, you can download the technical sheet below for free.

DIY wood filler problems -conclusion

Wood filler is a great tool to have around the house. There are many how-to videos and articles circulating showing you how to make homemade wood filler as an alternative to this. DIY wood filler is cheap and will convince many to use it, including me. I’m definitely not against it, but if you will use it, you should be aware of some DIY wood filler problems.

Now that you’ve read through the information in this article, you’ve seen the DIY wood filler problems that can arise when using it. I am sure that, thanks to this knowledge, you will undoubtedly be able to make a more conscious choice between professional wood filler or homemade wood filler for your next projects.

If you want to delve even more into wood fillers, take a look at my article, — “What Wood Filler Is The Best To Use? 3 Types Clearly Explained!” There I go into much more detail about the use of wood fillers and the different types of wood fillers and wood putties. I highly recommend it if you’re looking for information on how to find the right product for the job you’re working on.

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I hope these 5 common DIY wood filler problems will give you insight into whether you should continue to use homemade wood filler or not.

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Christophe, founder of Christofix.com
Woodworking | DIY | Home decoration

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