Forming a Film for Irritation-free Hair Removal

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Title: Forming a Film for Irritation-free Hair Removal
chemical depilationx thioglycolatex emollientsx calcium thioglycolate hydroxidex
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Whether their hair is fine or coarse, blonde or black, many female consumers struggle with facial hair. If they choose to remove it, courses of action include epilation, chemical depilation, manual depilation and shaving. To avoid the discomfort of manual depilation and ensure long-lasting effects, many women choose chemical depilation. Like most methods of hair removal, however, chemical depilation is known to cause skin irritation, mostly due to the highly acidic ingredients used to break down hair bonds. While this irritation can be concealed on the body, it is much more noticeable on the face, posing a challenge for women who wish to conceal their depilation efforts as well as formulators creating chemical depilatories.

Siân Morris, PhD, and her R&D team at Procter & Gamble (P&G) believe they solved this dilemma with the development of the Olay brand Smooth Finish Facial Hair Removal Duo, a two-product system that removes facial hair while preventing irritation.

Balancing Act

The team sought to create a facial hair removal system based on an identified need. “Facial hair detracts from feminine, beautiful-looking skin. Women want to remove this hair but do not want others to know they do it, so we had to create a product that removed the hair [without causing] the redness and irritation associated with depilatories,” explained Morris. Following the first principle of medicine, “do no harm,” the team determined the best course of action was to prevent irritation in the first place, thus a post-treatment would not work for this application.

According to Morris, the basic chemistry of hair removal has changed little in the past 50 years, being based on a high alkylate pH technology. This same technology was used in the hair removal cream with tweaks to the balance of ingredients and retention of thioglycolate activity.

“The known fundamentals of hair removal are all here: a high pH to open the cuticles, penetration of the thioglycolate, disruption of the cysteine bonds between hairs and breakage of the weakened bonds as hair is wiped away,” said Morris. The hair removal system was developed to be effective yet gentle and is based on calcium thioglycolate hydroxide.

The novelty of the system was its focus on irritation prevention, which was achieved in a balm that was applied before the hair removal cream. To prevent irritation, the balm was designed to first deposit a fine-grade film on the skin. The hair would then stand up through the layer to be removed. That was the challenge, according to Morris, because it required a continuous but thin film.

“The product had to protect the skin but not coat the hair so that it could be targeted by the thioglycolate,” explained Morris. This required a balance of waxes, oils and emollients.

Irritation Protection

The balm was designed to act similar to the moisture barrier on skin, which is comprised of skin cells, oils and lipids. The balm creates a second layer on the skin surface that allows the hair removal cream to remove the hair above it but not affect the skin below it.

“The film had to lock the water-based hair removal cream out,” said Morris, who added there is a little occlusion but only for a short time. Locking the depilatory out of the skin is the beeswax, according to Morris. “It is important because it creates a continuous film with structure but keeps out the water-loving chemistry of the depilatory,” she noted. The beeswax is combined with sucrose polycottonseedate and soy extract, which help soften the skin to allow for a smooth, even application. A copolymer of Chinese wood oil and rapeseed also allow for a sheer, thin film. The film-formers combination mentioned above create a film that would not be possible with other waxes or emollients, according to Morris.

“We are using less crystalline waxes than petrolatum, which may lay down well but not offer a continuous film,” she explained. Crystalline waxes do not stick together well and require a thicker layer to protect skin.

“We wanted to avoid a thicker layer because the cream had to remove the hair as close to the skin surface as possible or [consumers] would not see results.” As directed, the balm is thus applied in circles to raise the hair slightly.

Future Developments

The two-step hair removal system was formulated for fine to medium hair; however, the company has found that 10–30% of women report having coarse hair, which could be higher depending upon how many women admit it.

“We know there is a range of hair textures, so we decided to take this technology and adapt it for coarse hair,” said Morris. To address coarse hair, the company adjusted the levels of calcium hydroxide in the hair removal cream.

“We took the same principle and rebalanced the formulation with calcium hydroxide so that we could increase the level of thioglycolate,” explained Morris, who furthered the thioglycolate had to be more fully deprotinated or more active. In addition, the company added sodium silicate to enhance efficacy, as it balances the thioglycolate phase.

The technology of preventing irritation before hair removal has potential in other sensitive skin areas, according to Morris, who could not discuss the specifics.

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Siân Morris, PhD

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