Soils from Hair and Cleaning Mechanisms

Cleaning Soils from Hair and Cleaning Mechanisms 

Hair soils may be classified as one of four different types  

Lipid soils are the primary hair soil and are principally sebaceous matter. For a more complete description of the chemical composition of sebaceous soil, see Chapter 2. 

Protein soils are from the skin but probably, in most cases, do not constitute a serious soil removal problem. 

Environmental soils vary and consist of particulate matter from air (hydrocarbons and soot) and minerals from the water supply. 

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Cleaning Soils from Hair and Cleaning Mechanisms 207 Table 5-9. Example of a deep hair conditioner. 

Cleaning Soils from Hair and Cleaning Mechanisms 209... 

Solubilization of hydrophobic soils is perhaps equally important to roU-up for shampoo cleaning. Shampoos are generally used at 1 to 4% surfactant concentration, well above the critical micelle concentration (cmc). In addition, shampoos are actually mixed surfactant systems consisting of mixed micelles, reducing the cmc of the system even further. Thus, hydrophobic soils of sebum and other oily soils can be solubilized by being incorporated into the structure of the micelles of shampoos. Solubilization is a very important mechanism for cleaning oily soils from hair during the shampoo process. 

More work is needed to determine the exact contribution of solubilization to the cleaning of different soils. However, solubilization is undoubtedly a highly significant cleaning mechanism and, quite likely, is the most important means by which shampoos remove soils from human hair. 

Solubilization by anionic surfactants is another possible mechanism for cleaning quats. However, Reich and co-workers [157,158] found that solubilization of CTAC and SAC by lauryl and laureth sulfates (1 to 5 EO) was ineffective owing to formation of surfactant-quat complexes that were insoluble in ALS or SLES and, thus, difficult to remove from hair. In this case, reducing the carbon chain length of the quat to 12 or the chain length on the anionic surfactant to 10 resulted in more soluble complexes and more effective removal of the cationic soil. 

The principles outlined in Section 3.6.6 apply to both the removal and anti-redeposi-tion of soils, and to detergency in both industrial and personal care situations. There are, however, some differences between the application of detergency in an industrial setting (Section 12.2.1) and in a household setting. For example, whereas industrial cleaning usually involves hard surfaces that cannot mechanically hold soil, fabrics can hold soil mechanically, even after the soil has been removed from the fibre surfaces. In addition, fabrics can usually swell in aqueous solution, are permeable to small molecules, and may contain charged or polar surface groups that can interact with soil. An effective shampoo or skin cleaner needs to displace dirt and keep it dispersed so it does not redeposit before the hair or skin can be rinsed. 

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