Priming MDF for Trim or Cabinet Grade Finishing

Written by on December 2, 2018 in Interior Products, Primers with 5 Comments

Oil-Based Primer: Still Necessary Sometimes

Over the past decade, we have shifted heavily from oil based paints and primers to latex technologies. We’ve tested and used many of the current generation of latex primers, always looking for one that can meet our interior and exterior priming needs. However, there are still times when oil is the only choice. Priming MDF is one of those situations.

priming MDFMDF, or medium density fiber board has become a common substrate for interior trim and cabinet grade surfaces. It is a very smooth surface, with no wood grain, but MDF is made up of wood fibers glued and pressed together. Don’t be fooled by the smooth surface, it is also highly porous. Be careful when prepping and priming MDF for paint.

You might be able to get a good latex primer to adhere to MDF, but it is not advisable. Latex introduces moisture to the surface, which causes swelling or a raised grain effect. This usually cannot be sanded out or corrected. Oil primers are the best choice for priming MDF.

The downside to oil primers is that they come with an odor, slow dry times and the need to use solvents to clean application tools. All of these things cost us time, and therefore money. While it is tempting to use a fast drying oil primer, we recommend that once you commit to using oil based primer on a project, choose well and don’t look for shortcuts.

Priming MDF with Benjamin Moore Fresh Start Oil Enamel Underbody

priming MDFThis product has long been our first choice for oil primer on interior trim/cabinetry because it is great on both wood and MDF surfaces. It is user friendly and doesn’t smell toxic. Enamel Underbody allows the user plenty of working time to spread and lay it off, so you can work at a comfortable pace. Focus on the quality of the base coat you are creating.

When using this product, allow plenty of time for drying in a warm and controlled environment. While the long working time with the product is great, it stays wet much longer than a latex primer would. This makes contamination a concern. So, try to minimize any airborne dust or debris that could settle into the finish while it is drying.

It will be slow drying, but cures and hardens to a desirable base coat that sands smooth and accepts water based or latex finish coats.

Application Tools for Priming MDF

WET

Priming MDF can be done with a brush, roller or sprayer. Your choice will depend on the scope and details of the task at hand.

We recently primed a batch of MDF cabinet doors and drawer fronts with BM Enamel Underbody. We chose to roll so that we wouldn’t have to spray oil and deal with the cleanup.

 

With a soft touch and the right technique, you can achieve a sprayed-looking finish using mohair or foam rollers.

[Learn More About Mohair Roller Covers]

How Do You Know When It’s Dry?

SandingUsually, the first place to look is the back of the can. Benjamin Moore is a little vague on this one, recommending that you allow this primer to dry overnight. But, you might be applying at 6:00 in the morning or 6:00 at night

Obviously, the primer doesn’t need to sleep, so our take on this has always been to give it 8-12 hours. When the surface feels dry and passes the fingernail test, it is usually ready to move into light sanding and finish stages.

When using oil primer, charge accordingly…it is not a fast turnaround. Sometimes it is just the right thing to do.

 

 

Scott Burt

Scott Burt is a contractor and freelance writer whose column "From the Field" has appeared in American Painting Contractor magazine (www.paintmag.com) since 2008. His writing and projects also appear in other print and digital venues. This site is an extension of Scott's publication work, and he encourages readers to leave comments and questions about articles published here. Hope to hear from you!

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  1. Scott Burt says:

    Shellac would be an option as well, if you don’t mind the smell or the cleanup when done. Some folks say it is too brittle as a primer for cabinets, but it does make for a nice base coat.

  2. Scott Burt says:

    Shellac is an option as long as its brittleness doesn’t become a liability. In theory, mdf doesn’t expand and contract, so there is that. But in humidity prone environments like kitchens or baths, it is worth thinking twice!

  3. Brewster201 says:

    I find shellac based Bin works well and dries way faster. Sprayed 2 coats and sanding 180 grit between coats

  4. handymanmike says:

    What about shellac?

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