The metallic ink typically contains aluminum flake pigments and a distinct layer which is overprinted with a layer of colored ink or as an element within the colored ink. In either case, they produce a very desirable appearance, exhibiting a shift in a color known as color travel dependent upon viewing angle. Although these colors are visually appealing, they can be challenging to characterize properly. While choosing an instrument that has to be used for measuring these inks, several things should be considered. Perhaps, the most important characteristic that needs to be considered is the geometry of the instrument which will considerably affect the outcome of the measurement. The geometry of any measuring device is defined according to the angle of illumination or angle of deflection.
The color measurement devices work on the basis of four basic geometries that needs to be considered when selecting an instrument. These core geometries are:
How to Choose the Right Geometry for Accurate Measurement
In printing, painting and graphical artistic, the manufacturers make use of instruments having 0o: 45o geometry and are used for the vast majority of measurement situations. These devices work extremely well in defining the color exactly as human eyes does. Moreover, the density related measurements such as trap, dot gain, dot area, etc. require the use of these geometries i.e. 45o: 0o or 0o: 45o.
Apart from these two geometries, the (d : 8o) geometry is used for textile, plastic and paint industries. This geometry helps to understand the diffuse illumination that allows for accurate and repeatable measurements if a wide variety of surface conditions which includes the difference in texture and gloss. These measuring devices have the ability to measure the colors of a sample in two modes that SCE – Specular Excluded and SCI – Specular Included.
From last so many years, the metallic coatings are used to give finishing touch to automotive. To measure the colors of these coatings, the Multi-angle spectrophotometers are accepted widely as it offers the best method to measure the coatings from multiple angles. These multiple color values can further be used to ensure the desired color is achieved at each angle and when the color changes due to the change in viewing angle the desired color can be attained and maintained easily and appropriately. When multiple angles are used to measure the colors of the samples, the main focus for color assessment is laid on 45o angle. This angle is referred as the face angle and the best angle that compute the best color from these metallic colors. The use of multi-angle instruments is successful for measuring automotive and decorative coatings; these instruments have different apertures to view the samples which sometimes prevent this tool for testing the color of metallic inks.
Testronix Instruments offers a wide range of color measurement instruments that works on different geometries and have different measuring apertures. For detailed knowledge, visit: www.testronixinstruments.com/