Polymeric capillary sealer for castings and composites allows visual inspection to ensure that porosity has been sealed. The sealer impregnates micropores and hairline cracks without vacuum or pressure, forming a protective barrier to gases and liquids that is not invisible when cured. Blue Dichtol penetrates up to 0.004” into the coating to prevent corrosion of the metal substrate. Pressure resistant to 8700 psi, and temperature resistant to 932°F (500°C), the product is suited for castings and composites. It can be applied by dip, brush or spray. It dries in minutes and cures at ambient temperature. According to the manufacturer, it increases machinability and dampens vibration to further enhance the utility of the components being treated.