How to seal MDF edges for painting

Sealing MDF edges for painting

If you have ever built a cabinet, counter, bench, or table out of MDF and then tried to paint it - you probably noticed very quickly that the edges suck up a lot of paint. This leads to repeatedly applying coats of paint or primer to the MDF, until it stops soaking all of your paint into the MDF. To avoid having the MDF suck up the paint, and to keep your primer and paint applications to a minimum, you can seal the raw edges of the MDF quickly and easily by following these steps.

Difficulty:

Easy

Instructions

Things You'll Need

• Yellow woodworking glue (titebond)
• small clear plastic dixie cup
• sharpie marker
• popsicle stick
• foam brush
• water
• newspaper or small dropcloth
• glass jar

1. MDF board raw edge

   Here is a picture of what raw MDF board edges usually look like. They are very porous and soft - and they absorb a ton of paint into the MDF piece you are working with. This causes you to apply more paint, and takes up a lot of time.

2. To seal the raw edges of the MDF board, we are going to create a yellow glue and water solution that can be brushed onto the edges of the MDF using a foam brush. In the next step we are going to create a mixing cup to make the solution. The solution is three parts yellow woodworking glue mixed with one part water.

3. Divide the cup into four equal sections

   Take a small, clear, plastic Dixie cup and using a sharpie - divide it in four equal sections and draw the lines on the Dixie cup. (see picture)

4. Divide the last 4th into 4ths

   Now divide the lower fourth into four parts and draw the lines on the cup. The reason we are doing this is because it really only takes a small amount of the glue-water solution, and I do not want you to waste glue. If you have a large project, it is always easier to make more of the glue-water solution! (see picture)

5. Excellent, now pour yellow woodworking glue into the cup so that it fills up three of the four sections you created in the lower 4th of the cup (3/4ths). The glue should be equal with the third line up from the bottom leaving you with one line left to fill in the lower fourth of the cup.

6. Now pour in enough water to fill up the last section. You should now have a full 1/4 of your overall Dixie cup composed of 3 parts glue and 1 part water.

7. Take the popsicle stick and stir up the solution so that it is equally mixed.

8. Now lay down your drop cloth or shop rag under the piece of MDF board that you want so seal.

9. foam brush

   Dip a small foam brush into the Dixie cup and into the water-glue solution.

10. Brush the glue solution onto the MDF edge face everywhere that the edges are exposed. Wipe off any excess drips or drabs with a shop rag.

11. Let this dry for at least two hours in a warm shop.

12. Now sand the edges smooth by hand with 220-grit sandpaper.

13. Prime your MDF board and the edges, let it dry, and you are ready to paint your finish coat only once!

14. Store any extra solution in an air-tight glass jar for a little while, but discard after use.

Resources

• My Woodworking Blog