What is Color?

What is influencing instrumental color measurement?

The spectrophotometers of today are very precise measuring instruments giving very accurate results that can be reproduced over and over again. It is not possible to deceive a measuring instrument in the same way as can often happen with a human observer. Use the figure on the left to see the effects of the background on identical gray dots.

Although the measuring instruments are very accurate, instrumental color measurement can be adversely affected by factors such as temperature, humidity and sample preparation. Temperature and humidity should therefore be monitored and a reproducible sample preparation process required in order to avoid measuring errors. This means, for example, that samples should be sufficiently conditioned before measurement so that temperature and humidity remain constant during measurement. Figure 2 shows how a temperature difference of 10°C can change the color of a sample. This would lead to completely different color values for one and the same sample.