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.

A statistical analysis for correlation approach to compensate the measured CIELAB colorimetric data for temperature alterations

“…In 1986, Verrill amended Fairchild's data using BCRA‐NPL Series II, and he claimed the new data had 5 to 10% less uncertainty if compare 20°C data with 35°C data . In 1997, studies conducted by Malkin revealed that colorimetric differences of BCRA‐NPL Series II color standards may serve as a function of temperature, using spectrophotometer with 0°/d, 0°/45° and 8°/t geometry . In this research and another book by Verrill in 1995, an assumption was made that it is possible to use the thermochromics data to correct for variations in temperature of the colored standards.…”

“…7 In 1997, studies conducted by Malkin revealed that colorimetric differences of BCRA-NPL Series II color standards may serve as a function of temperature, using spectrophotometer with 08/d, 08/458 and 88/t geometry. 8 In this research and another book by Verrill in 1995, 9 an assumption was made that it is possible to use the thermochromics data to correct for variations in temperature of the colored standards. In other words, the data can be used to correct the colorimetric data measured at temperatures other than 208C.…”

Reflectance factor measurement systematic errors due to near infrared fluorescence

“…The known thermochromic behavior of these tiles was not a factor in these measurements. 4 A second experiment was conducted where the set of BCRA ceramic series II tiles was measured using the NIST 0:45 reflectometer. 5 The illumination system consists of a spherical mirror focusing radiant flux from a source through an order-sorting filter onto the entrance slit of a 0.5 m double-grating monochromator.…”

Relative analysis of the dependency of spectrophotometric data on temperature using textiles, ceramics, plastics, paints, and printed materials

“…9,10 The color difference between the measured data at designated temperatures against the data at 20 C were reported by Compton, Fairchild, and Malkin et al In the 1990s, a series of studies were conducted by Verrill and Malkin at the National Physical Laboratory with 0 /d, 0 /45 and 8 /t geometry spectrophotometers, and some of the results showed that colorimetric values of ceramic color standards may serve as a function of temperature. 11,12 Recently, several publications concluded that a change in temperature only causes a slight hue shift in neutral colors. While some colors (eg, orange, yellow and red) are more sensitive to temperature change in terms of CIE L*, a*, b*, and C* data, the hue angle in CIELAB colorimetric data is an exception among ceramic tiles.…”