Sunday, September 12, 2010

Mixing powders

A big part of job security for color scientists is that the mixture of colorants is very difficult to predict. This is especially so in color printing with CMYK halftones. It is surprising to learn that this is not so for mixed powders: their color appearance turns out to be easy to predict.

In an article of the October 2010 issue of Color Research and Application, Kerui Zhu et al. study the Evaluation of Hunter color values L, a, and b of mixed powder. They mix carefully prepared powders of wheat, corn, soybean, defatted wheat germ, oat, and buckwheat.

They determine the color appearance of these powders in the Hunter Lab color space, also known as Hunter color values (HCV). Then they mix the powders and measure the mixed powders for various mass percents (MP). Statistical analysis reveals that there are good linear relations between HCVs L, a, b of mixed powder and MP of each individual powder. Thus, equations can be derived, which can be used as a simple method to rapidly evaluate the color appearance of mixed powders in various powder-matching processes in the agribusiness.

Click on the article title above to read the paper.