A.H. Lui, K. Greive
Consumers have a good understanding on the impact of incidental sun exposure on their skin. Therefore, sun pro- tection is often used for skin cancer prevention and its anti-ageing beneﬁts, with daily wear sunscreens forming part of many consumers’ skin care regime.
The efﬁcacy of a sunscreen relies on its ﬁlm thickness, uniformity, and adherence to the skin. Many consumers apply signiﬁcantly less sunscreen than the recommended dosage, thereby providing less protection than the labeled SPF. Furthermore, facial sunscreens are often used in con- junction with other products including moisturisers and foundations. The effects of these adjunct products on the sunscreen ﬁlm, and therefore the degree of sun protection, are unknown.
Therefore, this study investigates the effects of applying a moisturiser in conjunction with a non-water resistant facial sunscreen; and more speciﬁcally, whether the order of application affects the efﬁcacy of the sunscreen itself. Subjects cleansed their faces using the provided cleanser, applied a pre-determined amount of moisturiser or sun- screen, followed by the application of the same sunscreen or moisturiser respectively. Digital images were taken at set time points for the qualitative assessment the skin. In vivo SPF testing was also carried out after the application of the same moisturiser then sunscreen, and vice versa.
The order of product application was shown to affect the efﬁcacy of the sunscreen.