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Do You Need to Prime MDF Before Painting? (Answered)

MDF has topped peoples’ choice because of the numerous advantages it offers that too at an affordable cost. People love this engineered wood thus you’d see many house cabinets, and floors having this wood.

MDF is moisture-resistant and tough to break or crack while working with. It has clapped mostly for the work convenience it provides since MDF is very smooth to work with. You can cut and shape MDF wood and boards easily as its consistency is super fine.

MDF is used for different projects, indoor and outdoor. Though it comes in different colors, it can be painted over. But since it’s different from regular or natural wood, you may wonder if you need to apply primer over MDF before painting.

To clear your doubts and confusion, we’ve here tried to explain everything related to painting MDF.

Do you need to prime MDF before painting?

You need to prime MDF before painting to protect the wood and its finish. Though MDF is moisture-resistant, it’s vulnerable to water. Direct painting over MDF is not encouraged as the water of the paint affects the properties of MDF. That’s why a primer is needed to seal the wood before painting.

MDF or Medium Density Fiberboard is an engineered wood made by combining resin and wax with wood fiber. MDF is an affordable alternative to natural wood and is used largely in many outdoor and indoor projects.

MDF is a good and cost-friendly option if you’re looking for something durable. Though it’s not stronger than wood, it lasts for a good time as it has resin and is so moisture resistant. There is hardly any risk of using it in damp places such as the kitchen or washroom.

MDF is popular for its smoothness. The surface of MDF is smooth and even. It is so consistent and flexible that makes shaping and cutting the wood boards easy and less hard. 

Since the demand for MDF is very high this engineered wood material comes in different colors for users’ convenience. Even if you don’t find your desired color board, you can paint over it since the MDF surface is much more suitable for painting.  

However, you cannot directly paint over MDF boards or sheets. Because MDF is not water-resistant, it can only protect itself from moisture. 

So if you paint over it without keeping any barrier, the fiber of this wood will get affected and it may get damaged due to the paints’ watery consistency. 

Thus the MDF-made item will lose its durability and become useless. 

That’s why you need to prime MDF before painting. Primer coating will save its fibers from getting swelled by water or any other liquid and make it long-lasting. 

Is it necessary to prime the MDF board before painting?

MDF doesn’t resist water; neither it can absorb and tolerate it like other woods. So it’s necessary to prime the MDF board before you want to paint it.

MDF or Medium-density fiberboard is a wood material. It’s made of wood fibers mixed with resin and wax. It’s flexible, moisture-resistant, and has a very smooth finish to work with.

MDF is used largely for completing many projects. Moreover, it can be painted thus satisfying the user’s demand for a colored board. 

But MDF boards cannot be painted without any primer. Since they are not water-protected, the liquid and paint can go deep into the fiber layers through the board and thus ruin its texture.

If you prime the MDF board before painting, the coating of the primer will seal the surface and make it resistant to any liquid material. 

Do I need to prime mdf before spray painting with emulsion?

Yes, you need to prime MDF before spray painting with emulsion. Otherwise, the MDF board will soak up all the emulsion.

The emulsion is used as a topcoat to add shine. It’s water-based paint and adds durability since it can protect from moisture and humidity. 

MDF is moisture resistant. It can get away with damp weather but has zero-tolerance against water or water-based products. It can soak watery things very well. 

So if any water-based coating or layer is used over it, and will absorb it all. And then there will be swelling, uneven texture with bubbles and grain. 

But priming the mdf before using emulsion paint can prevent this damage. Though experts don’t encourage using emulsion or water-based products on MDF, you can use them after priming and sealing the MDF. 

What happens if you don’t Prime MDF before painting?

Often people skip the priming step while painting MDF to work with. They assume it’s not necessary to seal or prime MDF surface as it’s not natural wood. Some even compare MDF with plywood and don’t take the priming part seriously. 

If you too are planning to work with MDF and are not very interested in prime MDF boards before painting them, we’d like you to know what can happen next:

The wooden fiber will get bloated: 

MDF is a good absorbent. It can soak up any watery or liquid directly applied over the surface. But the fibers of MDF can’t tolerate water because it’s just moisture resistant.

So if you don’t seal the fiber-made MDF surface before putting paint over it, the surface will absorb all the paint but won’t be able to tolerate it. Thus the fibers can get affected, swelled, and bloated making the MDF boards non-usable.

There’ll be uneven texture: 

Since MDF can absorb water it will not leave the paint for similar reasons. But MDF is not waterproof, it’s vulnerable to fluid thus directly painting over it will result in grains, bubbles, and bloated surfaces.

The paint won’t stick: 

If you paint over Medium Density Fiberboard without sealing the absorbent surface, it will eat up all the paint. Without priming all the edges and sides of MDF, the paint will not stick to it. 

Even if it does after several coats, the color won’t look bright. That means painting over

MDF without priming will not give you the desired result.

Your project won’t last long: 

Even if you somehow manage to complete painting MDF without using a primer before, the project won’t be durable. As MDF will soak the paint it will be internally damaged. 

What is the best primer for MDF?

MDF surface is super fine for painting and adding new color. But since MDF can’t be painted without priming, you have to pick a good primer for the prep session. There are many MDF primers or sealers available

A quick-drying primer for MDF is Zinsser B-I-N Multi-Surface Primer. This is a solvent-based sealer that can blur out the porous surface of MDF quickly and properly. 

Rustin’s Quick Drying Primer and Undercoat is another primer and sealer. This acrylic-based primer comes in two shades so can be applied over dark color MDF too. 

For priming MDF, Leyland Trade MDF Primer is a good option. It’s a combination of primer and sealer. This one takes a bit more time but after two coats prepare the MDF surface for paint.

Besides, Blackfriar. MDF Primer Undercoat, Rust-Oleum primer, and KILZ interior primer are effective MDF primers.

How do you prime mdf before painting?

How well painted an MDF is depends on how well it was primed before the paint was applied.

If you are about to paint MDF boards but don’t have any clue how to use prime it first, here are the main steps that need to be followed:

Clean the MDF board: 

The first step would be to dust off the dirt, dust, and wood particles from the board. Wipe each side and edges of the board using a dry cloth. Place the board on a drop cloth for easy cleaning.

Choose your primer: 

There are many good MDF primers. Acrylic-based, solvent-based, etc. from popular brands. You can choose from Rustin’s Quick Drying Primer, Blackfriar. MDF Primer Undercoat, Rust-Oleum primer, or Leyland Trade MDF Primer. 

Prepare the edges: 

Apply a sealer on the edges to seal them. You can separately use a drywall compound or sealer plus primer for this step. Then sand the edges lightly after the sealer is dried.

Sand the board: 

Using 220 grit sandpaper lightly sand the whole MDF wood piece. Make sure there is no scratch or uneven surface. Wipe the dust.

Apply primer: 

Take any primer from the above list except the water-based ones for your MDF board. Apply it all over the MDF using a brush, spray, or roller. Let the primer dry and then re-apply. The MDF is ready for painting now!

Final Thoughts

MDF is a moisture-resistant engineered wood but it’s not water-resistant. Since it is super absorbent, paint over it can get easily absorbed. Thus the fiber will swell and the surface will be bloated and uneven. That’s why you need to prime mdf first and then paint over it.