New cosmetic silica upcycled from rice husk as natural alternative to microplastic powders.
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Presented by: Ingrid Vervier
With upcoming regulations limiting the use of several specific cosmetic powders in leave on applications due to their classification as microplastics, there is a need to find alternative powders that could replace those cosmetic powders longer term. Silica from rice husk origin is a natural and sustainable solution that can deliver optical benefit together with a good sensorial benefit. Thanks to its rice husk origin, the silica is outside of the proposed European microplastic restriction on solid polymers and meets multiple market trends such as non-GMO, natural origin and upcycled ingredient.
The purpose of this paper is to share how a cosmetic powder derived from a natural feed-stock waste can match or even exceed optical and sensorial benefits of the synthetic powders currently used in skin care and color cosmetic formulations. The evaluations generated on the neat rice husk powder and in formulations showed that it can bring multiple benefits such as water and sebum absorption, skin imperfections masking, skin mattifying, pores appearance minimizing, fine lines and wrinkles masking and compaction properties. In addition, this new silica has a smooth feel compared to traditional mineral sourced silicas that typically leave a dry after feel on skin upon application.
The rice husk cosmetic powder provides skin imperfection masking benefits (also called blur) in formulation by modifying the intensity of scattered/reflected light from the surface on which skin care products are applied. The higher the blur, the stronger the skin imperfections masking ability. This light scattering effect results in skin appearing more uniform, with less wrinkles, fine lines and pores. Several in-vitro tests were carried out to characterize light profile changes resulting from dispersing the rice husk powder either into the water or the oil phase of an oil-in-water emulsion. The optical profile was quantified through two main parameters: total light transmission percentage (translated in-vivo into a natural skin tone) and haze value (translated in-vivo into skin imperfections blur). Both parameters were measured on a standardized thickness wet film formed by coating the oil-in-water (o/w) formula onto a glass slide and allowing it to dry. The minimum screening thresholds considered were 70 and 93% for haze value and total light transmission, respectively. Formulas meeting those two requirements were then evaluated in-vivo by several panelists to confirm the immediate skin imperfections masking benefits. In-vitro evaluations showed that adding the rice husk powder into oil-in-water emulsion or anhydrous formulations was associated with a significant increase of the haze value. When used at 1.5% in an oil-in-water formulation, a higher haze value was obtained compared to both a hydrophobic mineral sourced silica formulated at the same use level but also polymethyl methacrylate (PMMA) or nylon-12 cosmetic powders used at 3 % use level.
The sebum and water absorption properties of the risk husk powder were evaluated in vitro. The principle of the test method used is to add respectively artificial sebum or water drop by drop to a standardized amount of powder and mixed to allow complete absorption. The amount of sebum or water absorbed is recorded per gram of rice husk powder. The trials demonstrated that the rice husk powder absorbs more water and artificial sebum than the mineral sourced silica, PMMA or nylon-12 powder.
The compaction property of the rice husk powder was also evaluated. The neat powder was added in metal cups submitted to a pression of 1.5 Tons, then dropped 3 times from a 30 cm height. The lower the weight loss, the higher the compaction property. The rice husk powder had < 1 % weight loss which can be translated into good binding property in formulation.
The purpose of this paper is to share how a cosmetic powder derived from a natural feed-stock waste can match or even exceed optical and sensorial benefits of the synthetic powders currently used in skin care and color cosmetic formulations. The evaluations generated on the neat rice husk powder and in formulations showed that it can bring multiple benefits such as water and sebum absorption, skin imperfections masking, skin mattifying, pores appearance minimizing, fine lines and wrinkles masking and compaction properties. In addition, this new silica has a smooth feel compared to traditional mineral sourced silicas that typically leave a dry after feel on skin upon application.
The rice husk cosmetic powder provides skin imperfection masking benefits (also called blur) in formulation by modifying the intensity of scattered/reflected light from the surface on which skin care products are applied. The higher the blur, the stronger the skin imperfections masking ability. This light scattering effect results in skin appearing more uniform, with less wrinkles, fine lines and pores. Several in-vitro tests were carried out to characterize light profile changes resulting from dispersing the rice husk powder either into the water or the oil phase of an oil-in-water emulsion. The optical profile was quantified through two main parameters: total light transmission percentage (translated in-vivo into a natural skin tone) and haze value (translated in-vivo into skin imperfections blur). Both parameters were measured on a standardized thickness wet film formed by coating the oil-in-water (o/w) formula onto a glass slide and allowing it to dry. The minimum screening thresholds considered were 70 and 93% for haze value and total light transmission, respectively. Formulas meeting those two requirements were then evaluated in-vivo by several panelists to confirm the immediate skin imperfections masking benefits. In-vitro evaluations showed that adding the rice husk powder into oil-in-water emulsion or anhydrous formulations was associated with a significant increase of the haze value. When used at 1.5% in an oil-in-water formulation, a higher haze value was obtained compared to both a hydrophobic mineral sourced silica formulated at the same use level but also polymethyl methacrylate (PMMA) or nylon-12 cosmetic powders used at 3 % use level.
The sebum and water absorption properties of the risk husk powder were evaluated in vitro. The principle of the test method used is to add respectively artificial sebum or water drop by drop to a standardized amount of powder and mixed to allow complete absorption. The amount of sebum or water absorbed is recorded per gram of rice husk powder. The trials demonstrated that the rice husk powder absorbs more water and artificial sebum than the mineral sourced silica, PMMA or nylon-12 powder.
The compaction property of the rice husk powder was also evaluated. The neat powder was added in metal cups submitted to a pression of 1.5 Tons, then dropped 3 times from a 30 cm height. The lower the weight loss, the higher the compaction property. The rice husk powder had < 1 % weight loss which can be translated into good binding property in formulation.