What is MDO?

What is MDO? That is a question that many woodworkers ask as they come across this peculiar product at a home center or lumber yard. To answer this question, it is first important to know that it stands for Medium Density Overlay. A woodworker might see the first words on the label “Medium Density” and jump to the conclusion that it is similar or the same as Medium Density Fiberboard (MDF), which is a purely composite material that is commonly used in interior cabinet construction. This is a valid comparison, and MDO shares some characteristics to both MDF and veneer core plywood.

Plywood, MDO, and MDF are similar in that they are both available in 4’x8’ sheets, and are commonly found in 1/2” and 3/4” thicknesses. But there are also key differences that buyers should be aware of as they consider which material to purchase for a project:

Plywood core vs. composite. One of the main differences between MDO and MDF is that MDO has a veneer plywood core, which makes it considerably lighter and easier to handle than MDF.

Moisture resistance. MDO uses waterproof adhesive to hold the layers together, making it resistant to delamination due to moisture exposure. This makes MDO an ideal material for painted outdoor projects.

Paintable surface. Compared to plywood, MDO has a smoother surface and makes for a better substrate for painted projects because no grain will be seen under the painted surface.

So, when you ask yourself what MDO is, remember that there are three key characteristics that make MDO a great choice for certain projects 1) lightweight, stable sheet material, 2) resistance to delamination from moisture exposure, and 3) it provides a great surface for painted projects.