Indigo belongs to the group known as vat dyes. These dyes are typified by the fact that they do not form a chemical compound with the yarn, instead adhering to its surface as a surrounding pigment.

Various substances can react with oxygen rendering them unusable, and amongst these are dyes for the textile dying industries.

As well as sterile operation instruments, hospitals and medical facilities need a whole host of hygienic aids and containers.

When producing hair dyes, hair tints and other hair care products, various substances, intermediate products and dye colours are mixed.

Drinking water is normally sterilised by chemical means or at the least with the help of chemicals, e.g. chlorine.