MDF (medium-density fiberboard) is not waterproof. It is made by combining wood fibers and resin using high pressure and heat, resulting in a dense and strong material.
However, MDF is not water-resistant and can swell or break down when exposed to moisture for an extended period of time. To protect MDF from water damage, it needs to be coated with a waterproof sealant or veneer.
It is important to note that even with a protective coating, MDF may not be suitable for environments with high humidity or frequent water exposure.