The optical properties of polymers, including haze, gloss, and transparency as well as the colour, are critical to many applications of commercial plastics. The transmittance of light determined by reflection, absorption and scattering. Plastic materials can be transparent, opaque or translucent. Different plastics also absorb light differently, which can also be influenced by the additives.
ASTM D1003 - Haze, Transmittance and Clarity
DIN EN ISO 2813, ASTM D 2457 and ASTM D 523 - Gloss