This document covers the determination of the total luminous transmittance, in the visible region of the spectrum, of planar transparent plastics and substantially colourless plastics, using a double-beam scanning spectrophotometer. This document cannot be used for plastics which contain fluorescent materials.

This document is applicable to transparent moulding materials, films and sheets not exceeding 10°mm in thickness.

NOTE°1°° Total luminous transmittance can also be determined by a single-beam instrument as in ISO°13468-1.

NOTE°2°° Substantially colourless plastics include those which are faintly tinted.

NOTE°3°° Specimens more than 10°mm thick can be measured provided the instrument can accommodate them, but the results cannot be comparable with those obtained using specimens less than 10°mm thick.