How To Fill Nail Holes In Mdf Trim: 7 Useful Steps

“Who will spend time filling nail holes? Rather skip it and start painting” – One of the common rookie mistakes.

What’s even worse, you will find your painting as crap at the end. “Why?” You ask yourself.

Well, the answer is quite simple. You haven’t filled the nail holes. Not only you, many people skip this part as this task is hard but to crack.

Don’t worry, because we have come here with an easy and fast step-by-step guideline about how to fill nail holes in MDF trim.

how to fill nail holes in mdf trim

Things needed to fill nail holes in mdf trim:

Estimated cost:$5-$20

Estimated time: 20 minutes

The time you need depends on your expertise level. If you are at a beginner level, then you will need 20 or more minutes. But if you are an expert on this type of work, then you won’t need that much time.


  • Putty knife
  • Clean cloth
  • Brush


  • Wood filler
  • Sandpaper
  • Window glazing

How to fill nail holes in MDF trim – In 7 Easy Steps

MDF is an engineered wood product made of wood fibers. They have been cracked down into small pieces and then mixed with wax and resins.

MDF boards are widely used for making furniture, home interior cabinetry, roofing, fire resistance, vapor repulsion, different projects, and so on.

Filling nail holes is necessary to get a perfect finish of the MDF board. The steps you need to follow-

STEP 1. Look at the size of the nail hole

How To Fill Nail Holes In Mdf Trim

Before starting any type of work, you must have a clear look at it. This is also the same for the task.

Your first task is to look at the size of the hole. Your first thought will be whether the hole is big enough for the effort of filling it.

It is a known fact that the holes will be visible if you look at them from close. For this, stand in such a position, from where others will judge at the surface. Then you must make a decision to fill it or not.

Now, if the hole seems visible to you, then shake your body for the next step. But what will you do if it is too small?

Well, in that case, you can start painting. But if you want a smooth surface like butter, follow the following-

STEP 2. Choose the correct wood filler

how to fill nail holes in mdf trim

There are two types of wood fillers—water-based and solvent-based filler.

Water-based fillers give a creamy and smooth density. They smooth up easily and can be cleaned easily. In comparison, solvent-based fillers are as hard as rock.

They are sticky and oily. They are way stronger than water-based fillers. But one thing to remember, if you want to clean, you must wait until it dries.

There are different colors available for wood fillers. You can choose any. As the filler will be covered by painting, so it won’t be visible.

But if your selected trim is pre-finished, you should choose a color that matches the board. For this, you can buy kits that include filler and colorant.

N.B: Caulk can also be used for filling. You can fill nail holes in trim with caulk But it will not give you the perfect result. You can not sand caulk as smooth as you can in filler.

STEP 3. Apply wood filler by your fingers

how to use wood filler on trim

For most of the holes, your finger is enough. As the holes are not that big in most cases, fingers are the best way to put the filler.

Now put a small dip of filler into your index fingertips. Then press it gently over the hole and swipe it. We suggest you overfill it, leaving a slight cliff over the area.

STEP 4. Apply wood filler with a putty knife(Optional)

How To Fill Nail Holes In Mdf Trim

If the holes are large and deep, then instead of your finger, a putty knife is suggested.

Dip a small amount of filler by the edge of the knife, press the filler gently into the hole. Then smooth the surface on top to remove leftover fillers.

N.B: Close the cap of wood filler between the time of applications. Because fillers harden rapidly.

STEP 5. Sand with your finger

If you are using water-based filler, then you can sand it with your fingers. After the filler has dried, then sand with your fingertips. Cotton gloves can also be used.

STEP 6. Finish it with sandpaper

How To Fill Nail Holes In Mdf Trim

For a professional finish, sandpaper is necessary. Use 180-220 sandpaper to give a perfect finish look. You should sand gently. You are just making it smooth and removing the excess fillers.

STEP 7. Clean the surface

Clean the surface with a clean cloth. Once it is cleaned properly, it is ready for priming and painting.


If you don’t have enough time in your hand, you can use window glazing instead of filler. It wouldn’t require sanding, and you won’t need to wait to get dry.

All you have to do is to take a clump of window glazing and squeeze it in your hand. Then push it over the holes using your thumbnail and sand with your finger.

Follow these easy steps to fill nail holes in MDF trim.

Frequently Asked Questions

Question: Can you use MDF trim in the bathroom?

Answer: Yes, you can use MDF trim flawlessly in the bathroom if you ensure proper ventilation and accurate sealing.

As the advantage of using MDF trim is, it doesn’t expand or contract like other woods. But the bathroom is a place of humidity, so you must be careful.

MDF trims can be damaged in moisture. If water enters the surface of MDF, it will end up swelling in the vanity.

However, don’t worry. Seal the backs and edges of MDF with an oil-based sealer and put a few coats of poly sealer as extra protection. Then your MDF is ready to be used in your bathroom without causing you trouble.

Question: Can you use wood filler on MDF?

Answer: Yes, you can use wood filler on MDF for better finishing results.

As you can see, the edges of MDF are a little tricky to paint. Because the end grains will come off while painting, and that would still be noticeable after sanding and a few coats of priming.

So, for a professional finish, you can use 2 part wood filler before priming. All you need is a wood filler, sanding paper, and good types of knives that come from metal.

Take a little amount of wood filler with a knife and mix it well with a brush. Then apply it to the board. Wait until it dries, and then sand it for a while. You will find the edge smoother.

Question: How long should MDF trim acclimate?

Answer: You must acclimate your MDF trim in the installing room at least for 24 hours. As you see, the MDF trim needs to get used to the moisture of the room.

MDF trims change dimensions depending on moisture content. If the moisture increases, the trim grows and vice-versa.

Before acclimating, follow this-

  • Do not store outside and directly on the floor
  • Leave the bundles wrapped for 48 hours before installation
  • Acclimatize in the installing room

Question: Can MDF trim be sanded?

Answer: Give your MDF trim the shortest look with 100/120 grit sandpaper. In one word, yes is the answer to your question.

You must sand it before and after priming. You can also use 200 grit sandpaper for sanding before putting primer. 

Remember, MDF produces a lot of dust while standing. These specks of dust can irritate your eyes and also lungs. For this, don’t forget to wear a protective face mask before sanding.

Final Words

Well, that’s it. Where there is perfection, there is satisfaction.

It’s a pleasure to have you in the whole quest on How to fill nail holes in mdf trim. We have covered everything from detailed procedures to time management.

However, our discussion comes to an end here, but we assure you to get the flawless filling of nail holes on the trim.

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