Colour measuring instruments - Spectrophotometers and Calorimeters.

The spectrophotometer will provide a complete curve for the reflectance of the sample across the colour spectrum and is thus a tool for complete characterisation of the sample.

A calorimeter is a photometer equipped with three or four specially selected colour filters for determining the colour of the sample more or less directly.

Generally speaking, the spectrophotometer is better for accuracy, and hence for absolute measurement, while the colorimeter is better for precision, and hence for differential measurements between two samples or between sample and standard.

For light colours, the precision of the modern colorimeter is better than that of the human eye. The eye is good at detecting small colour differences, but not so well at specifying them, and its colour memory is very poor.

Colorimeters are of established value for routine testing and control in the factory.