MDF, also known as medium fiberboard, is manufactured from wooden fibers, which have been compressed as well as bonded together with resin under high heat and pressure. Generally, these are squeezed & stuffed between two smooth, hard surfaces, which as a result creates a layered pattern on the edge. The grade of MDF is of utmost importance as it will, more often than not, dictate how good the finish will be. The higher the grade of MDF, the higher will be the density. Denser boards offer smoother finishes as there are more fibers compressed into them in order to provide a more even surface. Standard as well as premium grades are generally at the lower end of the density spectrum having Moisture Resistant as well as Industrial grades at the top.
Sealing MDF Panels Using Polyurethane
MDF is used for the majority of household applications which may include shelves and speaker boxes. It is easier to work with in comparison to regular plywood or particle board. MDF panels are extremely heavy that comes in varying sizes with 4 feet by 8 feet being a common size. Sealing MDF with polyurethane will help safeguard it from water damage.
- Sanding MDF Using 150-grit Sandpaper
Firstly, sand the MDF with the help of 150-grit sandpaper. Carefully, go over the entire area, that you are looking to seal, in a circular motion in order to smooth out the MDF. This will help make sealing MDF easier. Get rid of any remaining dust as well as debris from the MDF that is left over after you perform sanding. - Apply Solid White Primer To The Entire Panel
Now, spread a coat of solid white primer to the entire panel. Spray a wet coat of the primer on the MDF & make sure not to leave anything unprimed. Allow at least 30 minutes for it to fully dry. Touch to ensure that it is completely dry before moving on. - Sand Primed Area Using 220-grit Sandpaper
Next, sand the entire primed area with the help of 220-grit sandpaper. Complete this sanding process exactly in the same way as you sand using 150-grit sandpaper, going over the entire area in smooth circular motions. Once you are done with sanding, clean off all the remaining dust as well as particles. - Spray A Second Coat Of Primer
Apply a second coat of primer before allowing at least 30 minutes to dry once again. Sand down the surface in exactly the same way as the previous step, as soon as the second coat has dried completely. Wipe off the particles as well as dust from the MDF panel. - Apply A Coat Of Polyurethane To The MDF
Finally, apply a coat of polyurethane to the MDF with the help of a synthetic brush. Use smooth, even strokes and apply a top coat, making sure to cover the entire area of the MDF panel. Allow nearly 30-45 minutes for the polyurethane to properly dry before adding a second coat in exactly the same way as the first for complete coverage. Allow time to dry once you are done.