You might think that filling holes and gaps in wood is easy. Actually, whether you need to fill some nail, screw, or knot holes, it can be tricky to do so.
You may ask some questions like what is the ideal method for achieving a neat and smooth surface? What are the materials I should use? How to use wood filler for large gaps? And so on.
We will explain to you all these details in the article.
- 1 How to avoid gaps in the wood and how to use wood filler for large gaps
- 2 Why you need to fill the gaps in your wood trim
- 3 Guide to filling large gaps in wood using caulk
- 4 Common mistakes when using a caulking gun
- 5 Using wood fillers to fill gaps in wood
- 6 Commercial wood fillers
- 6.1 What to consider when choosing a wood filler
- 6.2 Drying time
- 6.3 Amount of filler needed
- 6.4 Form of the filler
- 6.5 5 of the best wood fillers
- 7 FAQs
- 8 Conclusion
How to avoid gaps in the wood and how to use wood filler for large gaps
When you are installing a trim piece, make sure the wooden parts are the right size, and they fit each other almost perfectly. Measure several times to be sure that the measurements will not fail you.
But in practice, you will not always achieve a perfect fit. So, you will often need to fill some gaps left in your wood trim.
In this article, you will find different ways of filling those gaps. It will help hugely if you are new to woodworking.
Why you need to fill the gaps in your wood trim
Large holes and gaps in trim are easy to notice and unpleasant to look at. They are obvious flaws that need to be fixed.
Besides the lack of beauty, gaps can let water through them and let them reach behind the wood trim. Water will cause the wood to rot, which leads to mold and bugs.
Repairing the damage is always expensive and frustrating, so it’s better to put some work in first to avoid lots of work in the future.
Guide to filling large gaps in wood using caulk
A simple caulk gun can do the job well. If you’re not familiar with it, here’s a step-by-step guide to using a caulk gun properly.
Get the accessories and tools
You will need the following materials to fill the holes in wood:
- Caulking gun
- Some piercing tools for the caulk gun
- Acrylic latex caulk with silicone (tubed)
- Painter’s tape
- Hand towels
- A bowl of warm water
As soon as you collect all the necessary tools, you can proceed.
Take the caulk tube and load it
First, cut the tip of the caulk tube at a 45-degree angle. This angle allows you to apply the caulk more accurately. Then take your piercing tool and pierce the seal.
Then load the caulk gun by placing the tube along with the slot and softly squeezing the trigger.
Use a painter’s tape
Attach the tape to each side of the gap or hole. This will prevent you from applying the caulk on the clean wood and making a mess.
Apply additional fillers for larger gaps
If the gap is really large, you can use some expanding foam to fill the space before caulking. The foam can improve the performance of the caulking significantly.
Apply the caulk to fill up the gap
Take your caulking gun and hold it against the trim at an angle. Apply a small amount of caulk evenly along with all the holes and cracks. Work in portions and do not rush it when filling a large gap.
Wipe the excess and refine
Wrap some cloth or a small hand towel around your index finger and soak it in warm water. Lead any caulk that missed the target into the gap and smoothen it. Remove the excess caulk with your finger, so you get a clean and smooth surface in the end.
Common mistakes when using a caulking gun
If you apply the caulk properly, you will get a smooth and durable result.
But if you make some mistakes along the way, the outcome might be not what you expected.
Applying too little caulk
Insufficient application of caulk leads to the formation of small holes and gaps. It is better to use a little bit more caulk than needed and then wipe the excess that didn’t fit into the gap.
Applying too much caulk
On the other hand, if you apply too much caulk, your work will look rough and sloppy.
The wrong angle of the tube cutting
The 45-degree angle we mentioned earlier is the perfect angle for a caulking tube tip. It allows you to control the contents of the tube, so you can apply the caulk carefully.
Rushing when applying caulk
Even if you’re dealing with a long gap, do not worry that the caulk will dry out quickly, and you will make it in time.
Apply the caulk in portions and do not rush it in one run! If you rush, you will only make more mistakes and leave some important sections unfilled.
Using wood fillers to fill gaps in wood
You can also use specialized products instead of caulking material. Those specialized products are wood fillers. You could either buy a commercial one or make it on your own.
Commercial wood fillers come in different types, and we will cover each one of them below.
Wood filler types
Choosing the right product might be difficult for a newbie – there are many kinds of fillers that are pretty distinct from each other.
Knowing what each wood filler type is well-suited to will help immensely.
Acrylic Caulk With Silicone
This works great for exterior wood since it is not easily damaged by moisture.
It is also well-suited to medium-sized gaps.
Wood Glue and Sawdust (Home-made)
This filler can be easily made with the materials you can find at your workshop.
It is prepared by mixing some Elmer’s wood glue and sawdust. It has some significant downsides though: the glue shrinks resists paints and stains and can become white after drying.
The filler is suitable for gaps no larger than about 3/8 of an inch. Filling holes that are larger will not give you a durable and smooth-looking result.
That’s why you shouldn’t use too much glue in the mix. Also, when working with sawdust, you must wear a mask to prevent inhaling the dust.
Cellulose Wood Putty
This wood putty consists of real wood pieces. You can use it to fill gaps in many wooden pieces, such as trim, closets, shelves, etc. The material is compatible with projects that are stained and covered with varnish.
The cellulose wood putty dries fast, does not shrink over time, allows you to sand it evenly, and does not resist paint and stain.
The downside of wood putty is that it is not suited to huge gaps and holes.
The paste consists of gypsum plaster.
It is a great choice for interior wood and is well-suited to filling small holes in wood trim, baseboards, jambs, etc.
The paste dries fast, allows you to sand evenly, and accepts paint and stain.
It tends to shrink over time, though, so you might need to apply another layer over the first one.
If you want to fix large gaps in your wood, then this option is for you.
The polyester paste works best for deteriorated wood. But you need to know that it contains potentially toxic wood hardener and tends to sag over time. That’s why it is often better to apply a second coating on it.
The paste and two-part epoxy have a similar application. But the polyester material reinforces the wood by brushing wood hardener, and then by a resin. The two-part epoxy does not have that feature.
Epoxy Fillers (Two-part)
The epoxy fillers consist of two epoxy parts that are put together into a flexible material that hardens over time. You can mold it before or after drying.
Epoxy is great for fixing extra large holes and gaps. It can be used to repair wood trims, door jambs, baseboards, moldings, etc.
But it takes a longer time for it to dry and harden (for up to several days).
Using wood fillers
When deciding what kind of filler you should be using, think about these factors:
- Size: the size depends on the nature of your gap. It might be a nail hole, a screw hole, or a knothole. It can also be a crack or some other kind of damage.
- Environment: it is important to consider whether the piece of wood is an outdoor or indoor one. The temperature fluctuations and humidity levels will affect the wood and the material you use.
Now you have all the things to consider when choosing the right wood filler for your case: the cons and pros of each type of material, the size of the gap, and the environmental factors.
But there are also some questions you might be asking. We will cover some of them down below.
What if I have an extra large gap?
Nail holes or screw holes are usually easy to fix. Water-based, petroleum-based, putty or homemade fillers would do well.
But things get a bit more complicated with larger holes.
Even for extra large gaps, you can use the homemade filler we described earlier. You can pick the wood dust of the color that matches your wood. You can then sand it and try to refine it with paint or stain.
Wood filler is great for filling large cracks in wood.
Epoxy or acrylic caulk with silicone fillers, latex-based fillers, and powdered fillers are also great options for large gaps.
All of them are durable and can be sanded evenly, painted, and stained. They do not dry out fast and get hard enough after drying. You can also drill into them if you need to join the wood parts later.
Tip. Get more useful information about the 10 Best sanders in 2023.
How to apply wood filler properly
All you need is to have some patience and follow the next steps:
- Dry the wood. First, if the wooden piece is wet, you need to dry it out completely.
- Apply the filler. Take a putty knife and lead the material into the gap or hole. Apply some force when pushing, so it eliminates all the little pockets of air. Use the knife to scrape away any excess filler. You can also wipe any remaining parts with a rag.
- Stain if needed. Take this step if you’re using a stain-friendly material and are planning to stain it.
- Wait for it to dry. Wait for the filler to dry out completely. After it has dried, sand the surface lightly. You can use sandpaper, or even a rasp or a file if you have applied an epoxy product.
The drying time depends on the type of material you are using. It can take anywhere between 15 minutes and 24 hours.
It also depends on the gap size and depth. The larger the gap, the longer it will take to dry out and cure completely.
Commercial wood fillers
What to consider when choosing a wood filler
The drying time of a filler corresponds to its storage life. If you want a longer storage life for your product, then you should not pick a quick-drying one.
The longer a material dries, the longer its storage life is. You can ask your seller for advice when you need to choose a filler while considering this factor.
Amount of filler needed
First, you need to be familiar with the situation in which you will be using the filler. Then you will know the approximate quantity required.
Form of the filler
You should also consider the duration and size of your projects.
If you are a professional woodworker, you will probably need to use the filler frequently. That is why you should use a ready-made paste, so you do not waste time preparing it over and over.
But if you are going to use the material for simple fixes at home from time to time, it is better to pick a powdered form to prevent early drying and hardening.
5 of the best wood fillers
Wood fillers come in all shapes and types in the market.
We have compiled a list of the best wood fillers that work great when used to fix large gaps.
1. Minwax 21600000 High-Performance Wood Filler
This 12-ounce Minwax filler consists of a 2-part compound that is really efficient as wood glue.
It is perfect for rebuilding, fixing, or restoring damaged or rotten wood, and can be used to repair wooden tables, chairs, woodwork, doors, windowsills, etc. You can also anchor some screws and strengthen loose connections in your furniture with it.
This product is water- and rot-resistant and can stick to pretty much any rough surface. That could be not only wood, but also concrete, ceramics, fiberglass, or metal.
2. Elmer’s E914 Carpenter’s Color Change Wood Filler
This product comes in different sizes – four, eight, and sixteen ounces. This allows you to choose the option that suits your case best. This Elmer’s product is perfect for woodworking at home.
When you apply it, you will see purple material in the affected area. But don’t worry – this Elmer’s purple glue will cure natural or white, and you will be able to paint or stain it easily.
The purple color allows you to see where exactly you have applied the material easily. You can spot all the areas and nooks that you have missed and fix them.
Once dried, the material absorbs stains well. If you let it sit longer, it will be easier to stain it.
The material is not toxic and accepts mild dyeing.
3. FamoWood 40022148 Latex Wood Filler
This FamoWood latex product is pretty airy and lightweight. You can work with it easily, even if unsanded, raw wood is used. You will not have to remove the paint from your colored wood piece.
For example, your furniture piece might have lots of vertical cracks. You can use this material to quickly fix all those flaws and make the surface look smooth and natural.
The filler dries quickly. Apply it in thin layers and wait for each layer to dry out before applying the next one. It imitates the wood texture and allows you to get repaired wood within just 15 minutes.
The material does not shrink or crack over time.
4. Elmer’s Products E848D12 Carpenter’s Wood Filler
This is a well-known Elmer’s product that is used as a household item for interior wood repair. That includes filling up holes and gaps and rebuilding damaged wooden pieces.
There is nothing that little Elmer’s solution cannot fix. It is available in a 12-pint size. You can finish your final form just by wiping the surface with a damp paper towel. Most of the time, you will not even need to sand it.
5. DAP Plastic Wood Natural Latex Wood Filler
This DAP product is latex-based and is composed of ‘plastic wood’. It is a high-quality material that imitates wood texture once applied.
It dries hard, and, if you use a thin layer of it, dries quickly. It resembles wood not only in terms of appearance but also in terms of the ability to be sanded, cut, planed, painted, stained, etc. You can nail and screw into it, too.
The material is durable and strong, but an epoxy filler would be stronger. If you want the material to act as a support, then you should choose latex-based products instead.
1. How do I craft and apply the glue-and-sawdust wood fillers?
We have mentioned this homemade material before in this article. Here’s a simple step-by-step guide to making it work:
- Prepare the white glue and sawdust;
- First, inject some glue into the gaps until it fills the volume that you want to repair;
- Apply a good amount of sawdust, so it covers the glue completely. Gently rub the dust with your fingers;
- Let the material dry and harden overnight;
- Sand any excess glue and sawdust manually to get a smooth surface.
2. Can I drill into wood fillers?
Some solvent-based fillers can hide any flaws well and can be used to make the surface smooth. But they lack the structural strength to withstand drilling into them.
But some other wood fillers are made for being cut, sanded, screwed, and drilled into. For example, the DAP latex-based product we mentioned in the article, or some acrylic or epoxy wood fillers are well-suited to those purposes.
You also should think about the type of drill bit you have. You want to use the one that is compatible with the specific material you’re using to fix the gaps.
3. How do I prevent my product from drying out?
Products in containers usually dry out after several months of storage. So do not buy loads of them if you’re going to spend only a small part.
But if you found that your wood filling has already dried, you can revive it by adding a small amount of water to the mixture in the container. It will rehydrate the material, so it could be used again.
4. Do I choose powdered or ready-made paste products?
It depends on your purposes.
The powdered form of material gives you the opportunity to measure the amount of paste you need for your specific task. The powdered form also does not dry out, which allows you to store them for a much longer time. Thus, if you need a material that you would use for simple home tasks from time to time, this option is for you.
The paste form comes in handy when you don’t have much time and need to repair something quickly. It has a shorter storage life due to drying out, though. So, if you are a woodworker who uses wood fillings a lot, you might prefer the paste form.
5. Can I use wood fillers to fix scratches?
Yes, you can use the products described above to repair scratches. Just apply a liberal amount of the material and then sand it until the surface is smooth.
It is important to choose the appropriate wood filler. The overall appearance of your work or piece of furniture depends on it.
After all, you might find the wood-filling task rewarding and pleasing. And now you know how to do it properly.
My name is Alex Mashinsky
I am an enthusiastic woodworking hobbyist who created topwoodworkingtools.com to provide helpful information and advice to fellow woodworkers.
The goal of the website is to help readers make informed decisions about woodworking tools and materials, with the ultimate aim of ensuring that they achieve the best possible results from their projects.
My main focus is on offering accurate, honest, and well-reasoned opinions and advice to help readers choose the most suitable tools and materials for their particular needs.