Natural Ingredients for Colouring Hair

This paper examines some of the existing methods for colouring the hair and skin using natural material (such as henna) and proposes a parallel technology that exists in the dyeing of wool and fabrics to extend the colour range. Many of the listed plants and their derivatives are not found in Annex IV of the Cosmetic Directive and may not be used as colours, however, they do have other properties which may justify their inclusion into a product for example as astringent or anti-inflammatory agents. The references and appendices have been excluded from this abstract. Introduction The dyeing of hair has been practiced since the time of earliest Man. When it was impractical to dye the hair, then the wearing of wigs was customary, even as early as the period of the ancient Egyptians. The use of natural dyes on the hair has not made very great progress, and this is due to a number of factors that should not be the reason for despair. 1. Natural dyes are not very stable in solution, are prone to oxidation, browning, discolouration, pH colour shift, fading and attack by UV light. However, none of these adverse effects are applicable to the dry powdered natural dye. 2. A single natural dye is not the right colour, and only henna or walnut seem to be suitable to colour the hair, perhaps with chamomile to tint blond hair. The answer appears to be quite simple and one should blend different natural dyes in order to create a new colour that would be suitable as a hair colourant. Consistency of supply One of the major problems is the functional part of the herb (i.e. the colouring dyestuff). The chemistry is not always known by the formulator and therefore the concept of a natural dye is rejected. In reality, many of the dyestuffs in natural materials are identified and can be quantified or standardised in the specification for the raw material. Some of these active dyestuffs are given in Appendix I. Notice that many of them have C.I. numbers (Colour Index) as well as food “E” numbers as shown in Appendix II. This list is far from exhaustive. Chemistry of Natural Dyes Carminic acid This extract is associated with the protein material of the cochineal beetle and gives red, yellow and orange colours depending on the products and pH. Coccus cacti or scale insects are insects that live and feed on the prickly pear cactus (Opuntia megacantha) of Mexico and Central America. They increase rapidly in size and lose their original shape until they appear as protuberances of the plant. The dried pulverised bodies of these insects yield the red dyestuff cochineal, which the Aztec Indians used as a body paint and for dyeing their fabrics a brilliant crimson. They also used cochineal for medicinal purposes. It has been used as a pigment and as a colouring agent in cosmetics, paints and beverages, but it is expensive as it takes 70,000 insects to make one pound of dye. The homoeopathic tincture is prepared from the dried bodies of the female insects, which are larger than the male and have no wings. It is one of the main whooping cough remedies. In both India and Australia attempts have been made to take advantage of this for the production of cochineal, for purposes such as dyeing soldiers' uniforms red. But chaos resulted. Either the insects fed so heartily that they wiped out the cacti; or the cacti multiplied so excessively that they became a real plague. This can be purified to yield carminic acid or reacted with alumina to produce the aluminium lake of carminic acid which is referred to as carmine. HOH2C