MDO (Medium Density Overlay) is an exterior grade plywood with a weather-resistant layer of resin-infused fiber that seals it from the elements. The overlay is 28 percent resin and resists water. MDO is used heavily in commercial sign making. MDO is made only with 100 percent waterproof glue. Our MDO is produced with a wood-colored overlay. The fiber-infused layer of MDO makes it especially easy to paint, and painted surfaces on MDO last up to three times as long as similarly painted plywood. It is used in all kinds of exterior panels, including fascia, soffit and siding.