Chapter 4 135 the unpleasant odor of ammonia that is present in some coloring products. These products will often claim on pack that they contain no ammonia. The monoethanolamine works in a very similar way to ammonia it raises the pH of the final mixed product to ~pH 10, aids the swelling of the hair and bleaching of the melanin. In general the higher lightening shades (light and extra light blondes) will still use ammonia as the alkalizer or in combination with monoethanolamine to ensure the desired lightening is achieved. Conditioning agents are often introduced into the tint to impact conditioning properties such as ease of combing, soft feel, and detangling during the rinse out of the coloring product. Examples of typical conditioning agents include cetyl trimethyl ammonium chloride, polyquaternium 10 and distearyl dimethylammonium chloride. A recent focus has been on strategies to improve the penetration of the dye precursors into the hair. The benefit is that the shade delivery will be more efficient, thereby reducing the cost of dyes required in the formulation. One strategy has been to use phosphate esters as materials to build a lamellar structure in the product which enhances delivery of the dye precursors to the hair.18 A second has been to use high levels of oil such as mineral oil or liquid paraffin to increase the hydrophobicity of the final tint-developer mix in order to favor partitioning of the dyes into the hair.19 In addition to the tint and developer bottles, many hair coloring kits sold in stores offer an after dyeing conditioner which allows for easy combing and detangling of the freshly colored hair. The product formulations are typically similar to a rinse-off conditioner, containing silicones and fatty alcohols as conditioning agents, but the levels of conditioning are higher. Recent innovations have been made to more efficiently deposit conditioning actives on hair that has been colored, taking into account the increased hydrophilic nature of colored hair. This has included the introduction of new silicones with amino-functionality that preferentially deposits on colored hair and also provides a hydrophobicity that is durable through several shampoos.20