MDF is usually composed of compressed wood fibers, wax as well as resin. It is regarded as a strong, dense and flat particle board, therefore, it is a great material to select when it comes to cabinets and built-ins that you are going to paint. The wax as well as resin on the surface will help safeguard the wood fibers from soaking up the moisture in water based primer/paint. The cut edges have exposed wood fibers that will soak up moisture when using a water based finishes, which in turn creates a really bumpy texture. This is particularly true if you route a profile onto the edge, trimming and exposing an even larger surface area.
MDF 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.
Painting An MDF To Get Smooth & Glossy Paint Finish
If you are looking to paint an MDF & want a smooth & glossy paint finish on the MDF surface, then there are three main ways to achieve this, as mentioned below:
- You can use an Oil Based Primer, as no water for the wood fibers to absorb, as well as no raised bumps.
- Cover the edges using Joint Compound And Sand Smooth before you start painting.
- Go ahead and prime the entire piece, edges and all using Water Based Primer before allowing those fibers swell.
As soon as the primer is completely dry, knock it down with the help of a sanding sponge. It doesn’t need much effort, as you simply need to sand over the little bumps as long as you have a silky smooth edge. If you used a lot of elbow grease during sanding process and re-expose more fibers so that you get more bumps when you paint, it should be very easy to bring it down before you go for a second coat of paint, or touch up that area. There is usually sufficient amount of primer still coating the MDF after the sanding in order to protect the fibers from the moisture in the paint.
Useful Tip
If in case the edge of your MDF has any saw marks, then it is important to sand those off before you paint, due to the reason that the paint will only accentuate the flaws.