For interior and exterior usage such as in cabinets and ducts, MDF should always be properly sealed. Probably the most common of all is the paint seal. MDF is hard, slick and flat and paints easily.

What is the difference between MDF and chipboard? Sealing particle board and an MDF board may seem like the same process, but ...

Medium density fibreboard--also known as MDF--is a popular building material for cabinet speakers, cupboards and bookcases. If the unpainted MDF becomes wet or damp, mould and mildew can begin to grow ...