How to Fill Nail Holes in MDF Trim

How to Fill Nail Holes in MDF Trim

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If you are using MDF or medium-density fiberboard for the trim around doors and windows, then one of the things that you are going to have to deal with are those pesky nail holes. Of course, you do need to use nails to attach that trim to the rest of your home, but with that being said, you obviously don’t want those nail holes showing.

Therefore, how to fill nail holes in MDF trim is what we are here to teach you to do today.

5 Best Materials for Filling MDF Trim Nail Holes

Now, what you need to know here is that there are a variety of materials that can be used in order to fill the nail holes in MDF trim. Let’s take a look at the best options that you have at your disposal.

1. Wood Filler

Wood Filler Perhaps the most popular choice to go with for filling nail holes in MDF trim is wood filler. Now, do keep in mind that wood filler comes in both water-based and solvent-based formulas, so be sure to choose a solvent-based formula so that it cannot be undone due to water or moisture.

Wood filler is a good option to go with because you generally just need to smear it into the hole and then let it dry. This is by far the easiest and most popular method to go with.

2. Wood Putty

Wood Putty What is important to note is that although wood filler is by far the best option to go with, the one thing it does not handle so well is moisture and extreme weather. Therefore, if you are filling nail holes in MDF trim and you are doing so for outdoor purposes, then the better option to go with is wood putty. Wood putty is a bit thicker than wood filler, and it is also more resistant to the elements.

Wood putty may be a bit more expensive, but it does also last longer, therefore making it a fairly cost-effective option to go with, especially if you are using it for outdoor purposes.

3. Spackle

Spackle Yet another good material that you can use to fill nail holes in MDF trim is some good old spackle. For those of you who don’t know, spackle is drywall filler. Drywall and MDF are of course two very different things, but with that being said, spackle does still work to fill those little holes.

Just remember that spackle usually always dries white, so you will have to paint over it afterward, or get a type that matches the original color of the trim. If you have some spackle leftover from doing your walls, then this is a perfect option to consider.

4. Wood Glue

Wood Glue Due to the fact that wood glue is not overly moisture resistant, it is not the number one option we would go with, but with that being said, if you do not have any wood putty or wood filler, then wood glue is another good option that you can go with. If you plan on using wood glue to fill those trim holes, you will need to first mix it with some very finely ground sawdust. Make a mixture out of wood glue and sawdust, and then fill the hole with it.

5. Epoxy Resin

Epoxy Resin If you are really in a pinch, and if you have nothing else at your disposal, then something else that you can try using is some epoxy resin. If this is the case, you want to fill those little trim holes with a little bit of sawdust and then cover them with epoxy resin. Just make sure that the resin you use can be painted over or else you will create a whole new problem.

How to Fill Nail Holes in MDF Trim

Now we are going to take you on a step-by-step tutorial on how to fill nail holes in MDF trim. For this process, we are going to be talking about either spackle or wood putty. Both of these materials require this exact same process in order to complete this task, which is why we chose to create the tutorial in this format.

Step 1: Sand the Holes

After you have inserted the nails, there may be some mushrooming in the wood surrounding the nail holes. Therefore, take some fine sandpaper and sand down the nail holes until they are completely flush with the rest of the MDF trim.

Step 2: Clean the Holes

Before you start filling those holes, you do want to make sure that they are perfectly clean. Therefore, you will want to use some pressurized air or a shop vacuum in order to suck or blow all of the sawdust out of the trim holes. You do not want there to be any sawdust or other debris present in the holes once you go to fill them.

Step 3: Apply the Wood Putty

Once you have chosen your wood putty, wood filler, or spackle of choice, you can then get to filling those holes. With your tool of choice, such as a small scraper or woodworking tool, you can apply a good amount of the spackle putty or filler to the nail holes. Make sure to completely fill the nail holes and then scrape away any excess. You will now need to let it dry for up to a full day, depending on the exact product that you used.

Step 4: Sand the Holes and Repeat

You now want to sand the holes down so that everything is completely flush with the MDF trim. Do keep in mind that spackle or wood putty may shrink a little bit, so you will most likely need to repeat this process. In other words, you will need to apply two layers of putty or spackle in order to complete this process. Once everything has dried, you can then sand it down one final time, and if needed, you can then even paint it.

Mistakes to Avoid, Tips & Tricks

Lastly, here are a few tips to make the process smoother:

  • When applying two coats or layers of anything, make sure that the first one is completely dry before applying the second one.
  • Make sure that the area you are working in is fairly dry and warm and also has good ventilation as this will help the spackle or putty dry much faster and better.
  • Keep in mind that in some cases you may need to apply a little bit of primer to the trim holes first in order to make your filler stick.


Now that you know exactly how to fill nail holes in MDF trim, you can get to making your house look as good as humanly possible. We don’t want to see any of those nail holes in your MDF trim!