Glazing Performance with MDF Versus Wood

Will a glazed finish hold up better on wood than it will on MDF? September 29, 2009

Question
I need informed people to respond to the argument stated by one of my builders. Last week I was questioned about painting and glazing an MDF door. The statement was that the introduction of glaze to a painted MDF door will cause me finish problems and that if I was to change to a real wood painted and glazed, this would take care of the potential problems. I was also informed that no other shops in the industry do a painted and glazed MDF door in a kitchen. I was told this is like putting a dress on a pig. Any thoughts? I would like to provide this builder with some facts, however he has been educated by my competition.

The second argument is about painting melamine. My competition paints melamine and we use a birch plywood and paint it. I was asked by this builder if I would agree that painting melamine is better that painting birch ply.

Forum Responses
(Finishing Forum)
From contributor L:
Painting and glazing MDF is probably more stable than putting the same coatings on solid wood. MDF will likely be a one piece door, therefore no movement between pieces will occur. This will eliminate any cracking that can occur with solid wood and floating panels. If you use the product correctly on MDF, it will last just as long as if it was on a solid wood substrate. This guy just doesn't like MDF, and neither do I. But for the argument he is using, it is hogwash. If the guy wants solid wood doors, let him have them. Just tell him there will be a premium price that comes along with them.


From contributor K:
Wood holds up better in a real world situation long-term. MDF is okay if it stays dry and is coated well. Painting melamine is crazy. The point of using it is so you don't have to paint. Paint would stick to plywood better than melamine anyway. If you try pre-finished plywood or melamine you won't go back to finishing the insides of the boxes.

From contributor B:
The only thing that is appropriate for painting melamine is using a primer that will adhere to it. Then do your topcoat. There are several water base primers that will do it. There are solvent primers that will also, but these are found in your bathtub/countertop re-painting supply houses usually. But the question is, why paint melamine? I thought that's the reason for using it in the first place... to keep from painting the insides. Doesn't make sense to me to paint melamine.


From contributor R:
I've been finishing for going on seven years now and have worked in cutting edge, extreme high end shops (and learned from the best) and also in my own. Just so you know my background.

First off, the MDF and wood door have no difference in a quality glazed finish when applied correctly. Three things will normally cause a glazed finish to fail:
1) Excessive mil application (easy to do in paint grade application where you have to put down at least 2 coats of pigment, possibly a clear coat, glaze, and one or two more clear coats on top).
2) Heavy glaze application.
3) Glaze needs to bite and this usually has to do with recoat windows being correct. Many more failures occur on CV than, say, a pre-cat because of this.

If done correctly, I'd rather have the MDF in my own kitchen vs. a real wood door. Lastly, this builder is out of his mind to rather paint melamine than plywood (maple is better than birch, but birch is way better than melamine). Talk about adhesion issues.


From contributor A:
If you can find a primer that will adhere to melamine, all the power to you. Only one glue sticks to it. The acrylic waterborne primers will have the best chance. At the end of the day, why would you want to paint melamine? It will have that awful textured look, the one that makes me not use it in the first place. I would choose MDF over wood, simply because it is more stable and doesn't have joints. Also, when we build paint grade 5 piece doors we always use MDF flat or raised panels, then glue them into the wood groove. The GC is a yahoo. Do what he wants and let him pay for the consequences.

From contributor O:
As a seasoned finisher I have done many upon many glazed cabinets and doors, some made with MDF doors and some made from solid wood. The MDF has its advantages. If I was going to do this project I would do it the same way I have done it for years and as far as I know I have no adhesion problems at all. I like to seal in my glaze coat with a coat of vinyl sealer. To the vinyl sealer I add some retarder. The retarder slows down the drying time of the vinyl sealer and in doing so, it allows the vinyl to melt my glaze into the base coat that I am applying my glaze to. On top of the dried vinyl sealer, I will top coat with conversion varnish.

Most GCs know very little about finishing, so I would make samples for them using the same steps on the sample that I would use on the project. If your GC wants something done that you yourself cannot stand by, you might want to add a disclaimer to your sample board and have the contractor sign off on it.


From contributor E:
Glaze goes on after the door is sealed. The substrate doesn't matter, and therefore will not cause any more problems than glazing anything else, as long as it's done properly, and you sand it so you get adhesion.

As far as particleboard holding up in a kitchen, it doesn't matter what you coat your doors with, or if it is hardwood/MDF. If it has a floating panel and a lot of water gets into all the wrong places, that door is going to take damage. But real wood does hold up better in reality.

Plywood is stronger than melamine, but when painted, there's a good chance you're going to see the birch grain in your finish. If you painted melamine, it's going to look more like laminate. It may look odd if everything is smooth like laminate, and then you see random areas where wood grain shows. Adding a glaze will worsen this effect.


From contributor J:
Why would anyone paint melamine? For that matter, why would you paint birch plywood? Isn't that what pre-finished is for? If you want to paint something, nothing paints better than MDF. I've seen one high-end cabinet company that paints and glazes over alder veneered MDF. But that's because they do a rub-through on edges and beadboard routering to expose natural wood.
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