Paint Finishes on Wood or MDF
I recently had someone contact me with questions about painted cabinets. I have copied over my response to them below and I hope it is useful to others. A little background first, though.
Painted solid color cabinetry is very popular now. To get a solid color you can either use paint or tinted varnish. What's the difference? In simple terms, any solid color finish is a combination of pigment (color) and solids content (which is the "armor" that protects the color and gives it a sheen). Industrial grade paint is composed of pigment and a high solids content and generally 2 coats are sprayed on with no need for a primer (it is "self-priming). Tinted varnish is mostly all pigment with a low solids content. It requires a solid color primer to seal the surface, then the tinted varnish is sprayed over that and finally 2 to 3 coats of clear varnish are sprayed over that. So, it is less labor intensive to use paint and therefore less expensive. However, the tinted varnish process is much more durable and 2-3 times as thick as a painted finish. You can compare it to the "clear-coat" finish that car companies use nowadays. At The Cabinet Guy LLC we use tinted varnishes which we can make in any color that you can get with paint.
Paint or tinted varnish can be applied over any cabinet surface. Most manufacturers use hard maple but some use poplar or other "paint-grade" woods. Then there are others who use MDF - medium density fiberboard (in most cases that is what we use for our clients for solid color finishes).
The question that was posed to me was "Is MDF a good product for cabinet doors compared to wood for a solid color finish?" Here is my response:
"To me using MDF instead of wood for a paint surface can be compared to using metal or wood for your car fenders. Wood would be more expensive than metal in that case but it wouldn't be a better product for the application. When people say that MDF is "cheap" it would be like saying that metal is cheap when compared to wood for fenders just because it is less expensive. But less expensive in cost does not necessarily mean cheap in quality. You would be disappointed in how the wood reacts in a car accident compared to the metal and, likewise, people are often disappointed by how painted wood cabinets perform over time.
MDF is 50 pound density compared to about 20 pounds for hard maple and 15 pounds for poplar. That means the impact resistance of MDF to the rigors of daily use is much better than wood. Also, in my experience, a door made with MDF will last as long as a wood one and perform just as well. MDF does not shrink and swell with changes in humidity so the likelihood of cracks appearing at the joints is much less (which is very, very likely for wood). MDF is admittedly less expensive, about $1 per square foot for the raw material versus about $3 for hard maple. However, because it is a superior product for this specific application I would never call it cheap.
It is true that once a varnish is applied over paint it would be more difficult to repaint but the varnish adds years to the durability because it acts like a coat of armor (just like it does over a stain) and you shouldn't need to repaint for a long time. However, if you buy unvarnished painted cabinets you will find that the results of painting over them aren't any better and you would need to repaint them much sooner. The aim is to get a product that holds up so you don't have to repaint. That being said, you will find it difficult to get a varnished solid color finish from most manufacturers since it is too expensive a process for most of them. If you want a varnished paint look you will probably need to find a cabinetmaker who knows how to spray tinted varnish (not paint) and overcoats them with varnish like we do in our shop.
As to your question about the sheen level and how it relates to quality. Low sheen does not mean less paint or that it is a cheaper product. All finishes come in a variety of sheen levels. Sheen is measured as a percent of light reflectivity compared to a mirror. Low sheens have more pores so they capture more light rather than reflecting it. Dull or flat = 10-15% sheen, satin = 40-50%, semi-gloss = 60-70% and high-gloss = 80-90%. All sheen levels perform pretty much equally. It is simply a matter of aesthetics although high gloss paints tend to clean up easier because they are smoother since they have less pores for dirt to catch in.
I hope all of this proves helpful. In closing, let me say that six months from now when you are enjoying your new kitchen all of the headaches will be a dim memory so keep your eye on the goal, not the task. :)