ISO 22891

Description / Abstract: This International Standard specifies a method for the calculation of transmittance based upon diffuse reflectance measurements.

The use of the method restricted to white and near-white translucent papers. If it is necessary to determine the transmittance papers which contain fluorescent whitening agents, the fluorescence emission is eliminated using the prescribed UV cut-off filter.

NOTE This means that, although this International Standard refers to ISO 2469, which permits the use of both filter colourimeters and abridged spectrophotometers, a filter colourimeter with no means of eliminating the emission of fluorescence is not suitable for this type of measurement whitening agents are present.