TQC Sheen Permeability cups for determining the water-vapor transmission of paints, varnishes, coatings, coating systems and related products. The Permeability cup consists of a cup, seal ring and cover ring. The seal ring is designed to prevent turning when closing the cover. The Permeability cup is suitable for testing both self-supporting coating and non-self-supporting coatings. Water-vapor transmission is of interest for high humidity conditions. The wet cup method is thus the reference method for determining water-vapor transmission, if agreed up on otherwise, other procedures or conditions the dry cup method may be used.