MDF (Medium Density Fiberboard)
MDF (medium-density fiberboard) is made from pre-consumer recycled wood, usually saw dust from a saw mill or wood chips from lumber operations. The wood particles are mixed into a dough with a polymer binder (e.g., “glue” or “resin”) and consolidated under heat and pressure to form a panel.
MDF is a very nice prototyping material because it’s inexpensive, uniform in texture and color, and takes paint very well. Don’t confuse MDF with particle board – which uses much larger and looser wood fibers. It’s actually nice stuff, especially for laser cut prototypes. MDF is a little lighter (in both density and color) than high-density fiberboard (HDF), which is sold under the tradename Masonite, and sometimes called hardboard.
Laser cutting mdf works beautifully, with most lab cutters cutting up to 1/4 in and many cutting up to 1/2in or more. The laser does leave a dark charred edge. Most people leave it as is, but if you prefer, you can easily sand the edges to remove the charring.
We stock MDF in 1/8 and 1/4 nominal thicknesses. The actual thickness of the “1/8” is 0.118inch and of the “1/4” is 0.216in. Of course, MakerStock provides pre-cut mdf plywood panels in the right sizes for the laser cutter, or to a size convenient for your project.
MDF paints very nicely, but for most prototyping uses, you can just leave it as is.
The density of MDF is about 788 kg/m3 or 0.028 lb/in3, a bit more than the constituent wood because of the addition of the polymer binder.
Historically the glue used in MDF (and in plywood for that matter) contained formaldehyde, which could result in off-gassing and potential human health risks. Since Spring 2019, all plywood and MDF sold in the US must comply with quite stringent California and US regulatory standards. The level of formaldehyde is very, very low. (For the details, see https://www.epa.gov/formaldehyde/formaldehyde-emission-standards-composite-wood-products.)