MDF is made of compressed wood fibers, wax and resin. It’s strong, dense and flat so is a great material to choose for cabinets and built-ins that you plan on painting. The wax and resin on the surface protect the wood fibers from absorbing the moisture in water based primer/paint.
The cut edges have exposed wood fibers that will absorb moisture when using a water based finishes creating a really bumpy texture. This is especially true if you route a profile onto the edge, cutting and exposing an even larger surface area
How to Paint MDF
There are a few different ways to deal with this in order to get smooth edges.
- Use an oil based primer. (No water for the wood fibers to absorb, no raised bumps.)
- Cover the edges with joint compound and sand smooth before you paint. (I don’t do this as I think it’s too many extra steps…but it’s an option.)
- Go ahead and prime the entire piece, edges and all with water based primer and let those fibers swell. (My preferred method.)
When the primer is dry, take a sanding sponge and knock it down. It doesn’t require much effort, just sand over the little bumps until you have a silky smooth edge.
If you used a LOT of elbow grease when sanding and re-expose more fibers so you get more bumps when you paint, it should take very little effort to knock it down before you do a second coat of paint, or touch up that area. I’ve never had that happen though. There is generally enough primer still coating the MDF after the sanding to protect the fibers from the moisture in the paint.
(My CURRENT preferred Primer for MDF is Sherwin Williams “All Purpose Water Based Primer”.)
*Important Note: If the edge of your MDF has any saw marks, make sure you sand those off before you paint because the paint will only accentuate the flaws.*
Did you find this tip helpful? You might also like these other Painting Tips!
Samantha says
What perfect timing as I have some mdf to paint today and I was just going to look online to see how to deal with it! Thanks!!!
Tracie B. says
Great information to have. I’ve avoided MDF and plywood because of the edge problems. Thanks for filling us/me in.
Dixie Redmond says
Thanks for sharing this! I sometimes use MDF as a painting panel. It’s really nice to paint art on if it is primed and sealed well all around.
Gary says
Thanks Sandra! It is very much appreciated.
Gary
Ayisha says
Awesome advice. I can vouch for it too. A few months back, I asked your advice on this very subject on FB. It worked very well for me too. I also learned that sealing the cut edges of the MDF keeps it from seeping as much formaldehyde into the air.
By the way. My first ever build turned out great thanks to your advice. I’m in the process of putting my images together so that you can feature me. I don’t have a blog or anything but I’m so proud of myself that I want to share it with people who would appreciate my hard work.
Beckie says
You are just a wealth of information! Need any sewing help?
Shannon says
This is perfect. I am starting my first project with MDF this week. I had no idea it did this. My husband is out of town and I am tackling a small board and batten project in our entry way. You have inspired me to try projects on my own. We will see how it goes. I have my dad on back up if something goes wrong. Wish me luck!
Steph says
Do you find that you have an odor when using MDF? I agree that it is a great product to use but I am not crazy about the smell.
Sandra says
Raw MDF does have an odor. Once it is painted or coated, I don’t notice it anymore. If I use it for cabinets or built-ins, I paint both sides so it is pretty much completely sealed. I don’t know if MDF does or does not have formaldehyde in it, as someone mentioned earlier, but I do notice the “stink” until it is coated.
BPB says
You should not use water based primers on MDF, you should use solvent based primes to seal in the urea-formaldehyde gases released from MDF
Mohammadi says
Send me magazine of this subject if possible please
Rena says
Im confused. First you say: “1. Use an oil based primer. (No water for the wood fibers to absorb, no raised bumps.)”
But then you say to use a water based primer. Which is it??
Thanks for the help!
Sandra says
Rena, I offered 3 different ways to achieve smooth edges. Option #3 is my preferred method but there are other ways to do it.
Sam says
I am getting ready to tackle my first closet built ins and your whole site has given me SO much help and guidance! I am so glad you’re here and easily searchable!
Nicki Chadwell says
Hi thanks so much for the post. This is first attempt. I have used Zinsser 123 and yes got lots of bumps. Do you use a very fine sandpaper. I have 40/70/ 100 grit in my pack frim Wickes shoukd I use the finest 100??
Thank you
Nicki
Sandra says
Those are pretty rough grits. I use 220.
jack says
ive heard sherwin-williams has a new paint especially for MDF do you know anything about it?
Sandra says
I haven’t heard anything about that.