Bleaches formulation requirements

In hair coloring a light ash blond shade may require as Httie as 0.5—1% of intermediates, whereas a tme black may require up to about 5%. In principle, the formulator blends precursors that yield red, blue, and yellow dyes. The base in which the components are dissolved or suspended is similar to that used in simple bleaches and may include alkanolamides, various types of surfactants, thickening agents, and solvents. Removal of undesirable dyes is achieved by treating the discolored hair with a powerful reductant of the sulfite family. 

This is a high-tonnage chemical and one of the most important of the bromide salts commercially. High-purity grades are required in the formulation of silver bromide emulsions for photography. The compound, usually in combination with hypochlorites, is used as a bleach, notably for cellulosics. The production of sodium bromide simply involves the neutralization of HBr with NaOH or with sodium carbonate or bicarbonate. 

It also keeps the pH buffered in the alkaline range required for the peroxide bleaching of pulp. Sodium silicate has also become an important ingredient of the chemical formulation for the de-inking of printed waste paper. 

Liquid detergent process patents frequently define both compositional and process requirements, such as raw material concentrations and specifications, order of addition of critical components, thermal history, premix or adjuvant preparation methods, product/process stabilizers, distributive and dispersive mixing requirements, and process instrumentation. These patents apply to the production of primary raw material constituents, such as surfactants, builders, conditioning agents, rheology regulators, hydrotropes, disinfectants, bleach additives, etc., in addition to the specification of fully formulated detergent systems. 

For permanent hair dyes where small shade changes to a lighter color are required, bleaching is also involved. For these systems of permanent dyes, extra peroxide is formulated into the creme developer for the necessary bleaching action. For formulas of this type, see the section of Chapter 6 that describes the formulation of permanent hair dyes. 

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