MDF is medium-density fiberboard, a popular material used to mass produce furniture. Manufacturers make MDF using glue and very fine wood residue. The wood residue comes from the mill ends of dimensional lumber and logs that sawmills reject for other uses.
MDF offers several advantages. Its cost is about 10 percent of dimensional lumber's, and it's free of knots and similar imperfections. With paint or lamination, it is difficult to distinguish engineered MDF lumber from the natural product.
MDF is susceptible to water damage. Manufacturers must drill pilot holes for screws they use to hold it together, or it splits. An automatic nail gun works much better than a hammer if nailing the material. The material also off-gases formaldehyde. Painting MDF seals the formaldehyde inside, but inexpensive MDF furniture often skips this step in favor of laminating the MDF. The laminating material does not seal the formaldehyde inside the wood.
Manufacturers generally sell MDF in 4-foot by 8-foot sheets. For 3/4-inch stock, a single sheet weighs over 100 pounds. Choosing half-sheets or quarter-sheets makes it easier to work with the material. This same weight makes boxed assemble-at-home furniture very heavy. Consumers should enlist a helper when transporting these kits or moving MDF furniture.