For industry, it is difficult and time-consuming to guarantee a constant colour quality for special-effect varnishes within the production chain – from the pigment to the varnish and then to the finished product. It is nearly impossible to reproduce existing special-effect varnishes whose exact composition is unknown.
As numerous wavelengths have to be determined for an angular resolved absolute reflection measurement with a defined angle of incidence and of reflection, such measurements have so far taken several hours or even days. A line scan camera at the new robot-based measuring set-up “ARGon3” (3D Appearance Robot-based Gonioreflectometer) of PTB now reduces the measuring time to just a few minutes, as it can detect a whole spectrum at the same time. It is supplemented by a luminance camera that improves the previous spatial resolution from 20 mm to about 30 µm and thus provides clearly more detailed colour information from a test sample.
The colour coordinates determined here ensure that industrially used colour-measuring instruments are able to provide more precise and comparable data. Thus, the quality control of colours can be improved – both for conventional and for special-effect varnishes.
andreas.hoepe