Computer colour matching has become one of the standard methods in the paint, plastics and ink industries for fast and accurate recipe prediction. The advantages when compared to manual matching include better first shot accuracy, reduced number of corrections, exact prediction of metamerism and price, and thus higher efficiency and productivity. A colour matching system consists of a spectrophotometer, a PC and the matching software itself. The major differences between systems are the spectrophotometer, the calculating algorithm of the software, the software features and user-friendliness of the software and, last but not least, the ongoing service and support offered by the supplier.

Equal strength of all components

The accuracy of a match is dependant not only on the software and its mathematics but also on the accuracy of the calibration samples, the reproducibility in production and between the laboratory and the production. The quality of production can only be influenced by the user of the matching system. However the reliability of the measurements directly depends on the instrument used. In this context, the short- and long-term repeatability of a spectrophotometer is very important as is the inter-instrument and inter-model agreement.

This is especially important if the measured data is to be exchanged between a number of instruments. Konica Minolta, one of the leading manufacturers of radiometric instruments, offers a wide range of portable and bench-top spectrophotometers, which have a strong reputation for their unmatched inter-instrument and inter-model agreement. This is achieved without special adjustment. In addition they offer perfect data compatibility between measurements using different aperture.

The engine in the background

A critical case in colour matching, which cannot be solved by standard matching software, is matching of products which are neither opaque nor transparent, but translucent. In theses cases, not only the colour but also the opacity has to be matched. This cannot be achieved with the commonly used Kubelka-Munk-Model or Lambert-Beer Law. Other physical models have to be found to describe the complex effect of absorption and scattering of such layers.

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