Dyes and color index( CI) numbers

The color index is produced jointly by SDC (Society of Dyers and Colourists) in the UK, and the AATCC (American Association of Textile Chemists and Colorists) in the USA. The index is split into two parts: one part gives the commercial names for the individual dyes; the other part of the index gives the color index number, and lists the commercial names for the dyes using that number. 

Color index number

Every dye is given a color index number based on its chemical type. The same number is given to the dyes with the same chemical structure. For example, Resolin Red FB and Dispersol Red B2B, both have the color index number “CI Disperse Red 60." The index number is divided into four sections: 

1) CI stand for color index and is displayed in every color index number 2) The next section is the dye type, e.g., Disperse, Acid, etc. 

3) The third section is the color, according to a defined list of color names, e.g., Red Yellow, Orange 

4) The last number is increased every time a new dye is added to the index; in the example above, “CI Disperse Red 60" is the 60th red disperse dye to be added to the index. 

As an extensive international compilation of the structure and properties of dyes and pigments, as well as a system of numbering these materials, the Colour Index is a potentially valuable tool for all users of colorants.

CAS numbers for chemicals and chemical compounds

CAS Registry Numbers are an important tool for substance searching. These are unique identifiers assigned by the Chemical Abstracts Service (CAS) to specific substances identified by them in the chemical literature.

Registry Numbers save you from having to think of all the different synonyms, trade names, or possible systematic names when you are doing a compound search by linking them all into a single search term.

For example, there are over 20 synonyms for formaldehyde, e.g., methanal, formalin, methyl aldehyde. The CAS Registry Number for it, 50-00-0, is specific to all those names for the same compound.
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