Lets look at the different types of Sunscreen.
Oils are one of the oldest but most easily formulated sunscreen vehicles. Excellent product stability is achievable as there is only one phase. The manufacturing processes are simplified because the sunscreens and their additives are lipophilic in nature and are so soluble in sunscreen oils.
The ease of spreadability results in a very thin and transparent film and thus a lowered SPF. As no water is used as a raw material, sunscreen oils can be expensive.
Hydroalcoholic gels are the most common gel formulation used as the crystal clarity of cosmetic gel projects an aura of purity and elegance. They are refreshing on a hot day and the use of alcohol can reduce the need for additional solubilizers since most of the lipophilic sunscreens are readily miscible in ethanol.
Hydroalcoholic gels tend to cause facial and eye stinging on certain individuals. Upon exposure to heat and sunlight, the alcohol evaporates rapidly leaving behind a porous I discontinuous film, giving a lower SPF rating. Most importantly, high SPFs is difficult to obtain in this type of vehicle since the clarity issue rules out the use of good sunscreens such as octyldimethyl PABA or octyl p-methoxy cinnamate.
These products are very similar to those of the sticks. They are mainly mineral oil and esters which are thickened by petrolatum and some waxes. They are also water-proof but are oily and not very aesthetic to use.
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