Plywood is a type of engineered wood. It comes in various types and grades and is used for numerous industrial, construction and architectural projects. Medium density overlay (MDO) is an exterior-type plywood. It is overlaid (heat-fused) with a smooth sheet of resin on one or both surfaces. These surfaces can be painted and function as a water-resistant coating.
Properties and characteristics
MDO surface overlay is generally opaque and smooth. The surface veneer is typically wood-toned colour but other colours are also available. Manufacturers offer textured and factory-primed MDO plywood that is well-suited for siding applications (in homes) and painted signs. MDO plywood is chemical-resistant (it resists benzene, chloroform, methyl alcohol and acetone), weather-resistant and wear-resistant.
MDO plywood is available in standard thicknesses -- 6 mm, 1.2 cm, 1.8 cm and 2.5 cm (1/4 inch, 1/2 inch, 3/4 inches and 1 inch) and sizes -- 1.2 m by 2.4 m (4 feet by 8 feet). Various manufacturers provide customised sizes and thicknesses based on user requirements and specifications.
MDO plywood is specifically engineered for a range of outdoor and indoor applications, such as concrete forms, sign-use, storage bins, farm buildings, trailer and truck linings, factory work surfaces, countertops, and lawn ornaments. It is used in various commercial and residential construction projects, such as privacy fences, screens, chimney enclosures, garage doors, fascias and colour accent panels. Other interior applications include panelling, partitions and shelving. It is also used extensively in industries to make storage racks, display shelves, assembly benches and bins. MDO plywood is used in the construction of boats, caravans interiors and farm buildings (as interior and exterior walls).
MDO plywood is void-free and coated with a hard and smooth phenolic coating that easily accepts epoxy, paint and other glues. MDO plywood is cheaper than other types of plywood (such as marine plywood) and is easily available in timber yards. It is made with waterproof adhesive and resists surface penetration of water. It provides excellent sound and heat insulation and requires minimum maintenance. MDO plywood is also easy to clean.
The main disadvantage of MDO plywood is its bulk. It is heavy and not easily transportable. In addition, high-quality MDO plywood is expensive. Wood grain is evident in MDO plywood, and its surface smoothness doesn't make it suitable for interior decorative applications. MDO plywood dust is toxic and breathing protection (dust mask, goggles and the like) is required when working with it.