Color number (light)
A color number according to DIN 1557 a colorimetric characterization of optically clear, colored liquids EN (products). A characteristic value for the color of transparent materials determined by optical comparison under defined conditions . It belongs to the field of colorimetry .
The following color numbers are common:
- APHA -Farbzahl Hazen color number of (American Public Health Association)
- ASBC color number
- ASTM color numbers: ASTM D1500
- EBC color number
- Gardner color number
- ICUSMA color number
- Iodine color number (coloring of iodine )
- Lovibond color number
- Rosin color number
- Saybolt color number
- SAK 436nm
Color evaluation according to DAB 1996 and with photometric units of measurement ( transmitted light measurement ) are also carried out.
The color number is used as a quality feature, for example of raw materials such as fats and oils , resins , sugar, petrochemical products, brewery products, as well as of service water in the chemical industry .
The visual comparison with a standardized "color scale" is the easiest way to determine the color number. Devices for objective determination are based on the principle of a spectrophotometer (see also: UV / VIS spectroscopy ).