The expert working group 'Hair Care Products' of the DGK currently conducts a wide study to contribute to the understanding of how single hair fibre and hair collective properties contribute towards hair 'handle' and 'feel'. During the first stage of this study four hair types were selected from a large group of individual European hair braids, according to either similar or widely different panel ratings for handle. Against the background of the panel test and the state of the literature the working group readily identified the bending properties of single fibres interacting in the tress as a fibre collective and fibre friction as being of central relevance for hair 'handle' and 'feel'. Fibre diameters of the hair types were determined by Optical Fibre Diameter Analyzer and by weighing. From these data mean ellipticity and bending stiffness distributions were calculated. Single fibre friction was determined by the capstan method in the root, middle and tip regions. Significant differences were determined between the hair types in diameters, ellipticity, bending stiffness and friction. The results lead to conclude that 'handle' is perceived as inferior when the hair is thick and bending stiffness thus high. For such hair differences in handle rating are related to differences in friction, namely in the tip region. For thin and thus 'soft' hair fibre friction seems to play only a minor role.

The article contains sections titled: 1. Introduction 2. The Scalp and Hair 2.1. Structure of the Skin and Hair Growth 2.2. Structure of Hair 2.2.1. Morphology 2.2.2. Chemical and Physical Properties 2.2.3. Natural Hair Color 3. Hair Cleansing and Care Preparations 3.1. Shampoos 3.1.1. Composition 3.1.1.1. Surfactants 3.1.1.2. Other Constituents 3.1.2. Types of Shampoo 3.1.3. Dry Shampoos 3.2. Conditioning Agents and Treatments 4. Hairstyling Preparations 4.1. Setting Lotions, Mousses, and Restructurants 4.2. Hair Sprays 4.3. Other Hairstyling Preparations 4.3.1. Gels 4.3.2. Waxes 4.3.3. Emulsion‐Based Styling Products 4.3.3.1. Creams and Pomades 4.3.3.2. Gums/Puttys 4.3.3.3. Serums 5. Hair Coloring Preparations 5.1. Bleaching 5.2. Dyeing 5.2.1. Dyeing with Dye Precursors 5.2.2. Dyeing with Inorganic Compounds 5.2.3. Dyeing with Direct Dyes 5.2.4. Product Forms 5.2.5. Testing Hair Dyes 5.2.6. Dye‐Removal Preparations 6. Waving 6.1. Principles and Methods 6.2. Permanent‐Wave Preparations 6.2.1. Waving Preparations 6.2.2. Neutralizers 6.2.3. Notes on Use 7. Hair Straightening Preparations 8. Hair Removal 8.1. Epilation and Permanent Hair Removal 8.2. Depilation 8.3. Shaving Aids 9. Testing Methods 10. Toxicology and Legal Aspects 10.1. Toxicology 10.1.1. Introduction 10.1.2. Strategy for Safety Assessment of Cosmetics 10.1.3. Test Methods 10.1.3.1. Basic Principles 10.1.3.2. Systemic Toxicity Studies 10.1.3.3. Local Compatibility 10.1.3.4. Sensitizing (Contact‐Allergenic) Potential 10.1.3.5. Mutagenic/Genotoxic Potential 10.1.3.6. Reproductive Toxicology 10.1.3.7. Tumorigenic Potential 10.1.3.8. Toxicokinetics 10.1.4. Description of the Safety Assessment Process 10.2. Legal Aspects 10.2.1. General 10.2.1.1. Legal Aspects in the European Union 10.2.1.2. Legal Aspects in Other Countries 10.2.2. Individual Hair Preparations

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