Painting MDF Pressboard

Similar to the best practices blog regarding the removal of wallaper-with-steam, the purpose of the heat is to loosen/melt the glue in an attempt to get the adhesive to stick to the Thermofoil to be disposed of. Any glue remaining on the wood will need to be sanded.

It doens’t hurt to get the MDF damp, just don’t get it too wet.

Smaller blisters can be dealt with. Note though sanding won’t cut it. While the damage that you see is on the surface the risen aspect is due to damage from within. When particle board products are exposed to moisture, the wood wicks inward and then cellular wood fibers swell. This swelling causes the fibers to break the bonds with the glue/resins that hold it together. You can try to take a razor knife and cut v-sections into the board, to remove the lose/damaged sections. If the damage wasn’t too bad you can use a wood filler to repair the gap.

Sanding off any glue. Lightly use a de-greaser,… note glue residue can cause some paints to crack. Use wood filler to fill any voids. Any defects will become more visible after the paint is applied. If there is a blemish, we can probably fix that too. Let’s try to avoid any.

These foam brushes do an execellent job laying off the finishes. And clean-up is quick – just properly dispose of them. 

I’d recommend using a sanding sealer, perhaps Minwax Sanding Sealer as the the first coat. Another option is a paint primer that’s fast drying. Some people use a 50/50 wood glue-water mixture, although that isn’t as easy. The goal here is to prevent soaking while quickly sealing the surface with a thin fast-drying layer.

In this example, the paint is about as think as I would put it on. It’s not going to look good. You’ll be able see wood through the paint in places… That’s okay, right now we are just sealing the surface – without soaking the wood with a thick coat.

It’s your project, you may consider a second coat of primer before moving on to the finishing paint. Either way, it will more than likely be okay.

Regardless of the method that you are most comfortable with just remember the key take-aways

• Remove Thermofoil, dirt, grease…
• Quickly seal the surface with fast-dry primer or sanding sealer
• Paint in thin layers until you get the desired results