Human hair color account for all possible shades of brown, blond, or red (for example, platinum blond versus dark blond/light brown), nor does it explain why hair color sometimes darkens as a person ages. Several gene pairs control the light versus dark hair color in a cumulative effect. A person's genotype for a multifactorial trait can interact with the environment to produce varying phenotypes (see quantitative trait locus). Natural hair color can be brown, blond, black, red, or white; all natural hair colors including grey, white and lightest blond, are shades of brown. The Fischer–Saller scale, named after Eugen Fischer and , is
Colour sorter likely to fluoresce. In mining sorting industry, It is also called sensor-based sorting technology. Use Optical Color (CCD Color Camera) combineX-Ray Sorting Technology and NIR (Near Infrared Spectrometry) to pick out the impurity of ore, minerals, stone and sand products, separate ore into two or more categories. In the recycling industry, colour sorters can distinguish between coloured and colourless PET and coloured and colourless HDPE flakes, as well as being able to separate flakes by colour before re-granulation. Plastic colour separators are used to separate mixed-colour plastic flakes or granules. Plastic type separators (Sensor-based sorting technology) are used to separate