First off I want to say that I love, love, love your blog!
I am emailing you today to get your take on MDF Painted Doors with Glazing vs Painted Doors with Glazing that have a Hardwood Frame and MDF Center Panel. Are there pros and/or cons to either and is there one that you would recommend over the other?
I look forward to your input!
Sincerely, Stanley M.
Hi Stanley – thank you for your kind words. I always love to hear that readers like my blog and I love your question. Hold onto your hats because this is going to be a long one.
Let’s provide some background first so others might know what we’re talking about:
MDF or medium-density fiberboard, is a recycled wood product, densely packed with binders and resins to bind it together. The entire board is squeezed under pressure to be very, very dense.
Hardwood is actual wood – perhaps maple or birch or any wood with a tight grain – which is used for the frame, while the center panel is MDF.
So the question is why one over the other?
To answer this question, we first have to go back to why we’re not using woods in the first place.
Simple: wood is not a stable product. It expands and contracts according to humidity and temperature. Wood-workers were/are aware of this, which is why the center panel of any door is not fixed to the frame – it fits inside a u-channel of the frame which leaves enough space for the center panel to swell and shrink.
In the early days of wood-working, solid wood doors were made with the center panel (the middle section) out of an entire piece of wood, like so:
You can see how well that worked. As the panel expanded, it also warpedl..and that strain cracked the center.
So when someone talks about a “solid center panel” in a door, today's woods center panel are made by joining the pieces à la butcher block fashion. Each piece has the grain running the opposite way to its neighbor, which negates the major warping and cracking. Here's an example of an unfinished cherry panel with the joinery of the center panel:
See the darker piece next to the light piece inside that center panel? A center panel may be made out of as many as 6-8 pieces, depending on the width, and it's much less susceptible to cracking and warping like its early cousin was.
The frame construction of the door is called a mortise-and-tenon joint. Swelling or shrinking of the grain runs lengthwise (ever had your old interior doors on your house stick in the summer with a big gap in the winter? That’s why.)
Structurally, this is superior to a picture frame joint, where the corners of the door meet at a 45-degree angle, like so:
This style, while pretty, is more susceptible to the joints moving, because the grain expansion and contraction of the frame is pinched at the corners. See how that seam in right upper corner is more pronounced? None of the wood takes a poll and says, "Oh today we're all going to expand at the same time – let's go!" Each section will move and adapt in such a way that you might have all four corners opened, or none.
Now when we’re talking about applying paint onto the door with a glaze, this is why the MDF and hardwood centers and frames become important. We want to minimize that expansion and shrinkage – especially with glazes because as the center panel shrinks, it exposes a line where the glazing ends. I've certainly discussed with some worried clients over the years when we've had a particularly hot, dry summer! (It hides again in winter or more humid months as the center panel expands again.)
If I were to suggest which one I would use, I’d have to say it depends on three factors:
- Whether the frame is mortise-and-tenon, or picture-framed. The former could use either one, while I might recommend MDF for the picture frame.
- If we’re going to have cabinet doors as appliance panels on the refrigerator and dishwashers, MDF, while stable, is also heavy, and not all appliance doors can bear the weight of MDF-panels.
- How much we care about paint cracking at the seams.
Because it doesn’t matter how well the door is made – your climate, location, home humidity and even how you slam or don’t slam the doors will have an effect on the finished paint.
Outside of the U.S., many countries dislike the cracking and if I have clients from, say Canada or Europe, we might use the modern European methods for door construction: the doors are fabricated out of one piece of MDF – no seams, no cracking, and no worries.
Many Americans find this a bit too smooth, but everyone has their own preferences, right?
Hope this helps!