How to Paint MDF


Arriving at the painting stage of your woodworking project is rather exciting- especially after all of the hard work that has gone into crafting your piece. If you are using MDF, you might be more focused on not damaging the engineered wood with paint than anything else.

To paint MDF, you will need paintbrushes, sanding materials, personal safety equipment, and an MDF specific primer, paint, pre-sealant, and sealant. Avoid water-based paint and primers as the highly porous wood fiber and wax material will be distorted if it comes into contact with water.

Fortunately, painting MDF does not have to be overly complicated as long as you can take caution and heed the necessary steps. If you skip an action- like applying a sealant- you will notice that this type of engineered wood is not very forgiving, though. Still, take caution and use the recommended steps below, and your Medium Density Fiberboard project can turn out beautifully with a fresh coat (or two) of paint.

1. Gather the Right Supplies to Paint MDF

The first part of painting MDF (Medium Density Fiberboard) is to gather all of the necessary equipment. It is essential to understand what MDF is made of to know why certain materials must be collected and used instead of standard products used on other types of wood.

Specifically, MDF is Medium Density Fiberboard or engineered wood made with layers of wax and wood fiber. These layers are sealed together with high heat and pressure levels to become what you see available on the shelves.

However, this adhesion process makes this particular type of wood highly susceptible to water and some other chemicals and other elements such as extreme weather conditions.

Because of this, you will need to ensure that the materials you are using for painting MDF are specifically designed for this product.

Fortunately, there are some general supplies recommendations that you can follow (and should be able to find at local hardware or paint supply store). Since MDF is increasing in popularity, products can work well with this type of engineered wood.

That said, you will need the following supplies for painting MDF:

Paintbrushes

Be sure to opt for roller or bristle paintbrushes when painting MDF. You might get by with a sponge brush, but this is not ideal since the MDF material is already so porous. Choose high-quality paintbrushes for a high-quality paint job on MDF.

Sanding equipment. 

You will need to sand between primer and paint layers when working with MDF (similar to when working with other types of wood). This type of wood will not require high levels of sanding, considering it is already pretty smooth.

You will not have to tend to bumps and ridges in the natural wood grain, but you will need to smooth out the rougher edges.

The most efficient way to do this is with a Random Orbital sander. You can mainly use sandpaper at around 120 grit when sanding between primer layers and up to 320 (but 120 will probably do) grit between layers of paint.

Personal safety equipment.

 Specifically, while you are sanding between layers of primer and paint on your MDF project, you will need to ensure that you have a tightly-sealed mask as well as goggles to protect you from inhaling dust as well as catching it in your eyes.

You might also want to use some disposable gloves when smoothing out the project and getting rid of the dust, but this is not required. Just be sure to use caution when you take care of this (but more on that later).

Along with personal safety equipment, when you are sanding between layers on your MDF painting project, you will want to wear clothing that you are comfortable getting non-removable paint on. You should not have to worry about high toxicity levels if paint or primer gets on your skin, but you could see minor irritation.

For this reason, choose clothing that is not too loose (so that it does not sag into your paint) and that you do not mind being ruined should you splash some paint, primer, or sealant onto it.

Primer.

When you are painting MDF, priming the project is an absolute must. Otherwise, the paint will seep right through the porous material and will not stick. This can cause a catastrophic effect on your MDF project.

However, using an appropriate primer (including non-latex, non-water-based primers) will allow for the appropriate sealing and smoothing over your MDF needs before it is ready to be painted.

Also, keep in mind that you will need a separate paintbrush for your primer and other materials like paint and sealants that are applied. You do not want to mix these materials as they can alter or distort the final result.

Paint.

Of course, if you plan to paint your Medium Density Fiberboard, you need to buy the paint to do it. But, not just any type of paint will work.

You need to ensure that you are using a non-water-based paint considering the porous nature of the material. Opt for oil-based paint or even acrylic or latex paint. You can even find some MDF specific paint in much local paint supply or hardware stores.

Pre-sealant and sealant

Depending on what you plan to use your MDF project, you can determine how durable your sealant needs to be. However, regardless of what you plan to use this piece for, you will need to ensure that your material has been pre-sealed before applying paint and sealed after applying paint.

Pre-sealing is an important step to prevent the paint from being absorbed by the porous engineered wood. It will also allow the paint to stick to the wood more effectively rather than peeling off in an incredibly tacky and distasteful fashion.

A sealant will need to be applied to prevent natural wear and tear and exposure to elements like water from damaging your material after you have completed the MDF paint job.

Different materials can be used for both of these, but PVA glue effectively sealing MDF edges, and shellac can provide an effective pre-sealant.

You can then determine whether or not to use lacquer or polyurethane on this type of material, depending on how durable you need the piece to be. These will only need to be applied if you want the wood to be completely water-resistant since shellac can only provide a low-level to medium-level water resistance to wood.

2. Sand the MDF

As stated, under gathering the supplies, you will need to sand away the rough edges on MDF before painting it just like you would with any other type of woodworking project. When you are sanding MDF, it is important to recognize that this material is different from other wood types.

Because it has been engineered, it will not have the ridges that come from natural wood grain. Instead, you will find that the ridges will come where the multiple layers of wood fiber have been sealed together with a thin layer of wax adhesion. Sanding this down will not require an excessive amount of work, but it will still need to be done.

Additionally, you will need to pay special attention to the edges of MDF, as these will require the most sanding attention. This is where the layers will really showcase themselves, so they will need to be smoothed over.

Sanding MDF helps the primer and paint stick to the material more effectively. Still, it will help protect the material from being damaged by exposure to water and other elements later on.

When choosing the right materials for sanding MDF, you can generally sand the material manually for an effective sanding job using 120 grit sandpaper. You can also opt for using an electric sander, but sanding MDF will not require high grit or power levels. Just be sure that you pay attention to the edges and smooth out the rest of the material.

3. Remove Dust from Sanding

An important step that you must not forget, whether it is the initial sanding process or sanding between layers of paint or primer, removes the dust from sanding. If you leave dust behind, you can not only ruin the smooth surface, but the left behind dust can cause the paint or primer not to stick to the MDF. This can result in an incomplete or distorted process.

To remove the dust from sanding, be sure you are wearing your personal safety equipment. You can then either use a brush, vacuum, or another method of dust removal to ensure that there are no remaining pieces. After that, you are well on your way to applying primer and paint safely and effectively.

4. Prime the MDF for Painting

After you have sanded the raw MDF, it is time to begin priming the surface for painting. Again, you mustn’t use water-based products to ruin the material as they seep through the pores. Along with that, the shape of the piece will become incredibly distorted.

When choosing the right primer for MDF, you can find an MDF specific primer or use non-latex primers. You can also use solvent-based primer, although be sure to test on a small portion before applying it to the entire project. Since this primer is not MDF specific, there is no guarantee that it will work well on the crafting MDF piece.

With that in mind, you can test the primer on a small portion of the backside of your project (as long as it has been sanded just like the remaining portion of the project. Then, once you can confirm that this primer will work, you can begin using it for the rest of the project.

When applying primer, it is important to use it in thin layers. After sanding between each layer to remove discrepancies in the surface, you can apply another layer once it has dried. Ideally, you will use 2-3 thin layers of MDF specific primer before moving onto the painting step.

Finally, it is recommended to prime both the side that you intend to showcase and the rest of the project. This will enhance the MDF piece’s durability since the material is so naturally porous. Adding primer on both sides can help seal the MDF and prevent paint leakage when you get to that point.

5. Seal the Edges

Not only do you need to add primer to all sides of the MDF project that you are working on before you paint it, but you need to pay special attention to the edges of the piece. Whether you intend to paint them or not, the edges are incredibly rough and porous so that they will soak up paint and primer immediately.

That said, it is essential to seal them before you begin painting the wooden work of art. To seal the edges of your MDF structure, use PVA glue or shellac. In particular, the shellac can act as a pre-sealant that is applied before you add your final layer of sealant- such as a heavier-duty lacquer or polyurethane- to the project.

Be sure, when appropriate, to sand between layers that are applied to the sealant as well. This will allow for a more smooth and protected surface. You can then decide if you need to seal the entire project layer after the paint is applied.

6. Paint MDF with an Oil-Based, Acrylic, or Latex Paint

Now that you have primed and pre-sealed the MDF for painting, it is time to begin the step that you really came here for painting MDF. In choosing the right kind of paint, you can use oil-based paint.

It is essential to avoid water-based paint, considering if this gets through the sealant, it will altogether maim the MDF. Hence, an oil-based, latex, or acrylic paint is recommended for painting MDF.

Along with that, you will also want to keep in mind that a paint thinner will need to be applied (in opposition to water) if the paint you choose ends up needing to be thinner or fainter in color. Since adding water could ruin the MDF material by damaging the wood fiber and wax adhesion, it is essential to use the right tools.

As you are painting, be sure to apply thin layers and sand between each layer. You can use up to 320 grit sandpaper, but 120 grit should be a good place to start when working on your future item’s paint. Then, after applying 2-3 thin layers of paint, you should be getting close to the finish line.

7. Apply a Paint with a Preferred Finish

As you are using gentle and careful paint strokes in the above-mentioned step, you need to remember the final actions to lock this woodworking piece into place. Mainly, you will want to choose a paint with a finish based on the desired appearance. Some of the most common finishes include matte, ultra sheen, or somewhere in between.

You want to make sure that you can achieve the look you are going for in the beginning stages of applying a finish to your MDF project. Then, the final touches will not be quite so difficult. Again, it is important to test these out on small portions of a project rather than ruining the entire one.

8. Apply the Sealant to your Painted MDF

Once you have completed painting the MDF project you are working on, it is important to apply the sealant to lock in the richness and protection on your MDF piece.

Specifically, since this product has been engineered by wood fibers/wax, you will want to seal the edges to protect the material, coloration, durability of paint applied to it, and the woodworking piece’s longevity.

Applying sealant like shellac will allow for some water resistance, although the shellac’s water resistance is relatively minimal. Other options include using a more dense and controlled sealant like lacquer or polyurethane. However, if you do not intend to use your MDF piece for very many uses, they will not need this type of powerful sealant.

Regardless, be sure to seal all edges- including the unpainted edges- to protect the piece. Not only will you have the paint and primer sealed in, but you can prevent other types of disturbances such as water from ruining your hard work and dedication to your MDF project.

9. Store Your MDF Project in a Moderate Climate

Even though you have carefully applied primer, paint, and a sealant to your MDF project, you must store it in a moderate climate. Considering how the material is made- wood fibers being adhered together with wax, heat, and pressure- MDF is particularly susceptible to heat, water, and other elements.

Regardless of the piece you have used MDF to design and create; you want your project to be long lasting. With MDF, this is only made possible by storing it in moderate climates. So, ideally, MDF will not be placed in your sunroom.

And, even if you have used a strong sealant, avoid using MDF in locations like the kitchen or bathroom as even a tiny bit of MDF that is not completely protected can fall fate to exposure to water- even in small amounts.

Finally, you want to display the project where others can see it. So, instead of hiding it in the back of your closet and calling it an organizational cabinet, put the piece that you are proud of in your living room and let the praise roll in.

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