MDF is one of the nation’s favourite timber products; it’s cheap, easy to cut and join and can be painted. No wonder that it’s now more popular than solid timber.
Due to the absorbent materials inside the board, it’s also suitable for plastic veneers, and most adhesives work very well on it.
Unfortunately, the absorbent nature of the board does cause a few potential issues with certain paints.
Just follow the steps on this page, and your paint will stick securely to the MDF.
MDF Safety Concerns
MDF is manufactured from small fibres that are compressed to form a board; it’s also known as a Medium Density Fibreboard.
When cutting, drilling or sanding MDF, you’ll release dust that could be dangerous to your health if inhaled.
The binding agents (glues) in the boards aren’t pleasant, and while they’re perfectly safe inside the board, they are dangerous if inhaled.
One particular ingredient that is of concern is formaldehyde, and this has been classed by the EU as a carcinogen that is “suspected of causing cancer”.
As MDF board is used indoors, where ventilation is limited, you should use a suitable dust mask when working with this material.
You should first gently sand the MDF board with a fine graded paper, ideally with a sanding block – this keeps the surface flat and uniform.
Next, the surface should be wiped with a cloth dipped with a small amount of white spirit. Don’t pour the bottle onto the board as it may stain the board, just apply enough to dampen the cloth. Use this to remove the dust, oils and any contaminants from the area you want to paint.
Next, just let the board dry out and keep it on a level surface if possible.
Seal or Paint The MDF Edges First
Because the edges of MDF board are incredibly absorbent, you should seal them, even if they will be hidden from view.
To protect the edges and to ensure a neat consistent finish we suggest you either:
- Seal the edges with a quick-drying putty (such as this one) and sand down to leave a smooth finish or
- Apply several additional layers of primer and undercoat to the edges.
If you’re using MDF in an area where it may get damp (i.e. floor skirting or against an external wall), then you should also prime and undercoat the back of the board, even if it will be hidden from view.
Once the surfaces are prepared, it’s time to apply the first coat of primer.
The best product we’ve found is Blackfriar’s MDF Primer and Undercoat. It adheres well and is touch dry in 2 hours and re-coatable in 4 hours.
We suggest you apply the first priming coat a little thinner and the second undercoating layer at normal thickness.
Once dry, the MDF can be painted with your preferred top coat.
Painting MDF – Key Points
The method required to paint MDF successfully is similar to that used on other timber based materials, the differences are due to the absorbent nature of the material.
- Seal the edges of the board with extra layers of primer or optionally with putty.
- Paint the back of the board to prevent moisture ingress.
- Acrylic paints are the best primers and undercoats; Blackfriars is a great option.
- Use quick drying fillers, primers and undercoats to speed up the whole process.
- Don’t be surprised if the MDF absorbs a lot of paint, you won’t get much coverage from a small tin.
Benefits of MDF
Here are the key benefits of MDF and why it’s so popular:
- One the cheapest wood-based materials you can use for complex indoor projects.
- It’s strong.
- Can be cut with normal tools.
- It contains no grain, and the surface is even throughout.
- Other material can be screwed or glued to it with ease.
- Can be bent (kerfed) easily.
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