Evaluating Outside-in Skin Transparency and Other Literature Findings

By: Charles Fox, Independent Consultant

Posted: August 31, 2009, from the September 2009 issue of Cosmetics & Toiletries.

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Soybean oil in mascara: L’Oréal revealed water-based cosmetic mascara compositions with an emulsifying system comprised of a soybean oil derivative and/or a salt thereof.12 An example of a water-based mascara is shown in Formula 2.

Long-wear lip gloss: Revlon Consumer Products Corp. has patented a long-wear lip gloss comprised of styrene/acrylate copolymer.¹³ The invention reportedly retains gloss properties, comforts without irritation, and has staying power for up to 8 hr. An example of a long-wear lip gloss is shown in Formula 3.

Sunscreens
Polymer composite particles with a sunscreen agent: Sunjin Chemical Co., Ltd. has disclosed polymer composite particles containing a sunscreen agent with improved stability and UV absorption and the manufacturing method for this agent.¹⁴ Circular-shaped polymer composite particles, which are a hybrid of circular-shaped polymer particles and a sunscreen agent, reportedly improve dispersion stability of particles, provide UV absorption performance, and are applicable to cosmetics. These particles were created with: 13% w/w methylmethacrylate as the radical polymerizable monomer; 1.3% ethylene glycol dimethacrylate as the multifunctional cross-linking monomer; 0.2% 2,2’-azobis-2,4-dimethylvaleronitrile as the initiator; 4.5% butylmethoxydibenzoylmethane as the sunscreen agent; 0.3% polyvinyl alcohol as the dispersion stabilizer; and 80.7% ion exchange water as the solvent, with respect to 100% of total reactants. The ingredients were added to a detachable chemical reactor with an agitator. The mixed materials were emulsified and the temperature was raised to 60°C. The materials were then polymerized for 20 hr and the obtained polydisperse polymer particles were dehydrated by a decompression filter, cleansed by ethanol several times, and dried in a vacuum to form the final product.

Methodology
Evaluation of outside-in skin transparency: Mochizuk et al. published a method for the outside-in evaluation of skin transparency using a colorimeter and yellow food dye.15 Many reports exist concerning skin dysfunction in patients with atopic dermatitis (AD) due to impaired SC function. To examine this further, these researchers provoked skin with yellow dye and measured its color change using a colorimeter. A skin transparency index was then calculated by measuring the skin’s yellowing. Other variables of skin function, including transepidermal water loss and SC hydration, also were measured. The measurement of skin color using tartrazine showed good results and indicated a significant relationship between the skin transparency index and the AD score. The authors concluded that this method is noninvasive, safe and reliable for the evaluation of outside-in skin transparency and can demonstrate the characteristic dysfunction in the skin barrier of patients with AD.

Interesting Compositions
Transparent silicone oil emulsion: Beiersdorf AG disclosed a method for the preparation of transparent or translucent, silicone oil-containing emulsions for cosmetic use.16 A mixture of a silicone oil-containing oily phase and an aqueous phase was processed in several runs through a micromixer. The mixtures include substituted polysiloxanes, fatty alcohols, fatty acid ethoxylates, sunscreens, deodorants and surfactants. An example of a s/w emulsion is shown in Formula 4.