Hydrogenated oligodecenes and high-title physical sunscreens: new tools for safety

The requirements of an effective sunscreen include high solubility of organic filters in the vehicles, efficient dispersion of physical filters, absence of crystallisation after application onto the skin surface and lack of aggregation phenomena of micronised powders into product. Moreover, an effective sunscreen requires appropriate inorganic filters load as well as optimum wetting of mineral filters and the formation of a transparent limit layer over the skin surface. Photo-stability is another essential requisite for high SPF products. Nowadays, new synthesis and advanced purification process provide the formulator with pure, chemically defined hydrocarbon molecules having interesting potential for use in sunscreen products, high photostability and the capability to stay onto the skin surface without diffusing. New methods of micronisation and coating of physical filters provide a wide range of particles dimensions, different degrees of lipophilic or hydrophilic behaviour and enhanced transparency. When associated with branched chain hydrocarbons they yield an improvement in effect/dose ratio and form a very transparent film over the skin surface. Practical examples of formulation demonstrate the wide range of combinations made possible by such high-technology ingredients.