Woodworking Tips
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Medium Density Fiberboard -- MDF
It appears that more and more, we're using medium density fiberboard -- MDF -- to build jigs and other projects around here. And we've been getting questions about it. So here's a quick look at what it is, how to use it, and where to get it.
MDF is a manufactured wood product that's in the same family as particleboard. But unlike particleboard, which is basically a mixture of wood chunks and shavings held together with resin, MDF is a much more refined material. And the finer the material, the tighter it can be compressed to form a denser, stronger panel.

To give you an example of how fine the fiber is, it takes approximately 23" of fiber/resin mix to make a 3/4"-thick sheet of MDF. It takes only about 4" to 6" of wood chips and sawdust to make a 3/4"-thick sheet of particleboard.

Breaking down wood into a fibrous material has a number of advantages. First, there's no grain to it. This means that changes in humidity have no effect on MDF -- it's very stable. And second, the finer material results in a smooth, flat, uniform surface that makes it a perfect base for wood veneer and plastic laminate.

MDF can be worked like any other wood product as long as carbide cutters are used. About the only thing you shouldn't do is run MDF through a thickness planer or over an edge jointer. MDF is not usually stained or finished naturally. It's typically covered with wood veneer or plastic laminate, or it's painted.

And we've found that MDF takes paint well. Unlike particleboard or plywood where the surface texture shows through, MDF looks good with a coat of primer and a couple coats of paint.

Unlike plywood, a standard sheet of MDF is 49" x 97" (the extra is for trimming). Although it costs about twice as much as particleboard, it costs about half as much as a sheet of cabinet grade plywood.

The only problem with it is that it can be hard to find. Not all lumberyards carry it. Home centers rarely do. Try a builder's supply or cabinet makers supply. Or try one of these numbers from my rolodex to locate a dealer near you: NPA (301) 670-0604, Georgia Pacific (800) 284-5347, Medite Corp. (541) 773-2522.

Follow-up comments originally appeared with Tip #15: I mentioned how difficult it is to find MDF in some areas, I got an email from David and Amanda Brook. They say we should try living in Australia or New Zealand sometime. MDF, they say, is everywhere. It's real wood that's hard to find!

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