OH-542-PTD is a type of low-moisture blocking primer from LMB, which is designed for use in creating waterproof and chemical-resistant protective coating for a variety of surfaces. It is a one-part, water-based, non-flammable, alkyd-urethane blend that is highly resistant to sunlight, extreme temperature, water, and chemical spills. It can be used as a primer, a sealer, or a topcoat and can be applied to a wide range of surfaces. The product is manufactured and distributed by LMB and can be purchased directly from the manufacturer or through select retailers.