Color Measurement of Painted Metal Plates

Sensor Instruments GmbH: The color of metal plates should be measured immediately after the painting process. It must be taken into account here that there are both high-gloss surfaces and very dull surfaces, and that the color value must be determined irrespective of the gloss factor. Furthermore, measurement must be performed inline, on the one hand to satisfy the requirements of 100% inspection, and on the other hand to be able to quickly respond to a possible color drift.

The recommended color sensor for this application is a sensor of the SPECTRO-3 series operating with the 45°/0° method (SPECTRO-3-28-45°/0°-MSM-ANA-DL). The sensor's distance from the object surface is 28mm, and the similar-to-daylight ring light illuminates the object at an angle of 45°, whereas color is detected at 0° from the normal. With this setup the gloss difference of different object surfaces is compensated to the greatest possible extent, and the color can thus be determined   without any gloss influences and with an accuracy of dE=0.3.

"Teaching" of color sensor SPECTRO-3-28-45°/0°-MSM-ANA-DL with the SPECTRO3-MSM-ANA-Scope Windows® software