Stabilisation of water-in-oil emulsions to improve - eTheses ...

occlusion, whereby a moisturisers is a product that adds moisture to the skin (Choi et
al., 2005; Ersser et al., 2009).
Emollients have three basic properties (Rawlings et al., 2004):
Occlusion – traps water in the skin via a layer of oil on the surface preventing
transepidermal water loss, thus increase the moisture content of the stratum
corneum (outer layer of skin).
Humectants – substances with water-attracting properties that increase the
water holding capacity of the stratum corneum (outer layer of skin). By either
attracting moisture from the dermis to the epidermis or attracting moisture
from the environment to the epidermis.
Lubrication - adding slip or glide across the skin.
2.4 Lip Physiology & Emollient Therapy
The outer layer of the lips (stratified squamous epithelium), as shown in Figure. 2.5,
is devoid of the horny stratum corneum layer according to Harry and Wilkinson,
(1973); whilst Ryu et al., (2005) state that the stratum corneum is relatively thin in
comparison to facial skin. Either way, as a result the lips appear translucent and red
due to underlying blood vessels and a lack of keratin (Kobayashi & Tagami, 2004).
As a consequence of this deficiency in keratin (partially-keratinised), these outer
cells known as corneocytes must be kept moist in order to prevent drying, wrinkling
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