14 September 2008

Skin CareVehicle for sunscreen is as important as the effectiveness of the sunscreen system chosen. One of the water soluble and easily washed off the skin is sunscreen spray milks.

Blend cyclomethicone, stearyl methicone, menthol, and ethylhexylethoxycinnamate as the sunscreen, produce O/W microemulsions. Various surfactants/lipids/sunscreen were characterized by microscopy and laser light scattering.

This following formula is one of the stable O/W microemulsions that were waterproof and had a great humectants.

Skin Care Product
Ingredients% Weight
Surfactant/lipid70:30
1:2 Hexanediol30
Water62.2
Decylpolyglucose2.5
Soya lecithin2.3
Cyclomethicone0.55
Ethanol0.25
C12-15 alkyl benzoate1
Ethylhexyl methoxycinnamate1.2

There is no risk of the oil-soluble sunscreens not being adsorbed into the skin, since microemulsions are one-phase systems.

There are two factors that determine whether an emulsion will be O/W or W/O :
  1. Phase volume
  2. Surfactant used
Sun CareSun care products means positioning the sun filter to absorb or scatter UV rays. Conventional O/W vehicles fall short in that the sunscreens are found in the internal phase, as stated previously. At the other side, W/O vehicles are more effective. Its sunscreens are more effective coz the sunscreen was in the external phase. Usually, this sunscreen are more water resistant. The problems is, higher concentration of the lipophilics, means higher cost of the formula.

This problem can be slove. To reduce the cost, incorporating a polymeric surfactant such as PEG 30 dipolyhydrxystearate. The cost advantage of using this surfactant is that it allows formulating W/O close to the cost of O/W formulations. The incorporation of inorganic sunscreen into the formula is also enhanced due to the dispersing property of the surfactant.

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