This part of ISO 5631 specifies a method for measuring the colour of paper and board by the diffuse reflectance method with the elimination of specular gloss.
It can be used to determine the colour of papers or boards that contain fluorescent whitening agents, provided the UV content of the illumination on the test piece has been previously adjusted to give the calibrated colourimetric value corresponding to CIE standard illuminant D65, using a fluorescent reference standard with an assigned CIE whiteness (D65/10°) value provided by an authorized laboratory, as described in ISO 11475.
This part of ISO 5631 is not applicable to coloured papers or boards that incorporate fluorescent dyes or pigments.
ISO 5631-2:2014 Referenced Document
ASTM E308-06 Standard Practice for Computing the Colors of Objects by Using the CIE System*, 2024-04-20 Update
ISO 11475:2004 Paper and board - Determination of CIE whiteness, D65/10 degrees (outdoor daylight)
ISO 13655:2009 Graphic technology - Spectral measurement and colorimetric computation for graphic arts images
ISO 186:2002 Paper and board - Sampling to determine average quality
ISO 187:1990 Paper, board and pulps; standard atmosphere for conditioning and testing and procedure for monitoring the atmosphere and conditioning of samples
ISO 2469:2007 Paper, board and pulps - Measurement of diffuse radiance factor
ISO 2470-2:2008 Paper, board and pulps - Measurement of diffuse blue reflectance factor - Part 2: Outdoor daylight conditions (D65 brightness)
ISO 5631-1:2009 Paper and board - Determination of colour by diffuse reflectance - Part 1: Indoor daylight conditions (C/2°)
ISO 5631-3:2014 Paper and board - Determination of colour by diffuse reflectance - Part 3: Indoor illumination conditions (D50/2 degrees)