Chapter 10 357 increased swelling, slight uplifting of the cuticle scales, and a rougher feel. It appears that consumers essentially use the words “conditioning” and “moisturizing” interchangeably. In their minds, a rough, course hair feel (presumably the consequence of a degrading cuticle structure) is equated with dryness. It is likely that this belief arises due to an analogy with skin care, where a similar thought process persists. Therefore, this symptom is actually alleviated by lubrication rather than any true mitigation of moisture content. As described in Chapter 3, conventional conditioner products are extremely effective at masking poor feel properties and consequently, in consumer terms, the removal of this “dry” feel is described as “moisturization.” Manipulating the Water Content of Hair While current conventional treatments do little to alter the water content of hair, some non-conventional approaches are able to induce significant effects. If the “moisturization” term is taken literally, attempts at claim substantiation often involve the inclusion of humectants in a formulation. Humectants are hygroscopic materials that attract moisture, and so their deposition within hair may be expected to increase the overall water content (this said, it is worth highlighting the difficulty associated with depositing and retaining such water-loving materials within hair from an aqueous product that is applied in the shower). Nonetheless, Figure 18 shows how soaking hair in a 5% glycerol solution leads to increased water content at elevated humidity. (It is noted that an adsorption isotherm for glycerol and water is Type III in nature and therefore the anticipated hygroscopic nature only arises at elevated humidity). Similar, but lesser, effects have been seen with other humectant materials. Conversely, based on ideas outlined above, it is very likely that reducing the moisture content of hair may be more desirable. Namely, lower water levels appear to improve feel, while also increasing tensile properties. There is precedence in the scientific literature for this occurrence. Perhaps most notably, the ability for