How to waterproof MDF
MDF, or medium density fiberboard, is a very versatile, low-cost wood product with numerous applications such as shelves, cabinetry, furniture, and moulding. It is made from heat-pressed recycled wood fibres and resin and comes in laminate, veneer, and paint finishes. It is incredibly sturdy, easy to work with, and less likely to rip and crack. If you are working on a project in a high-humidity area, you must utilise or produce water-resistant MDF, or the material will deteriorate if it is continuously exposed to water and moist circumstances.
While it should never be used outdoors or in applications where it will be exposed to water on a regular basis, there are two methods for “waterproofing” MDF so that it may survive moisture in high humidity areas: Use moisture-resistant (MR) MDF or construct it yourself. It should be emphasised that regardless of the process used, MDF is moisture-resistant, not water-resistant or waterproof, and is remains prone to swelling and warping when exposed to the weather.
The first and most straightforward approach is to purchase MR MDF, which is intended for use in indoor settings where moisture is a concern. Moisture-resistant MDF is similar to conventional MDF in that it is easy to sand and mill, accepts most adhesives, veneers, and paints, but it is produced with a moisture-repellent resin. While slightly more expensive than normal MDF, the moisture-resistant characteristic makes it well worth the price.
You can also make waterproof MDF by applying a high-quality wood sealer, varnish, stain, or moisture-resistant paint to your project, allowing it to withstand moisture and humidity hazards.
Waterborne polyurethane should not be used since it may not adhere to the surface of the MDF.
To begin, use a latex primer or a primer developed specifically for MDF. Apply the primer with a 3/8-inch paint roller and a paintbrush to any spots that cannot be reached otherwise. Allow six hours for the primer to dry.
Step two is to use a 3/8-inch roller to apply the sealer or water-resistant paint. Paint the corners and edges using a paintbrush. This layer should dry in about four hours.
Step three is your final application of paint or sealer; let at least three days for curing to make the MDF moisture-resistant.