The BCRA–NPL Ceramic Colour Standards, Series II – Master spectral reflectance and thermochromism data

Abstract

The master set of the BCRA–NPL Ceramic Colour Standards, Series II, has been calibrated by NPL in the specular excluded, specular included and 0/45 geometries at a temperature of 25C. Tables of spectral reflectance and colorimetric data are presented. The thermochromism of the standards in the specular excluded geometry was also measured by NPL and the changes in spectral reflectance for a 10 degC change in temperature are given. The corresponding changes in colour data for the specular excluded geometry were calculated by NPL. Following a request from the Colour Measurement Committee of the Society of Dyers and Colourists, the corresponding changes in colour data for the specular included geometry were calculated by the Scottish College of Textiles on the assumption that the changes in spectral reflectance are the same for both geometries. Thus changes of colour data are presented for the specular excluded and specular included geometries. It has been shown by Ceram Research that it is possible to use these thermochromism data to correct colour data measured at an arbitrary laboratory temperature to a standard temperature.