SUN CARE HYDROLIGHT INITIAL HYDROLIGHT AFTER 30 MIN MAUI MILK INITIAL MAUI MILK AFTER 30 MIN


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Figure 3: Avocado experiment images.


variety of product forms. Many producers are realising the benefits of


natural clays in sun care products - from high end luxury brands to mass market consumer products and baby care products. Clays work by forming a network within the formula. Within this network, the clay can suspend particles and actives to create stable homogeneous products. Elementis clays generally have a smaller particle size. Smectite clays play a key role in enabling


product formulators to achieve significant skin-feel enhancements and texture variations. Hectorite is one the most efficient rheological agents of the smectite clay family due to the large surface area and uniform charge distribution. Elementis owns a hectorite mine in California in the western region of the United States. A hectorite clay additive developed by


Elementis that is vegan and COSMOS approved, Bentone Hydroclay, has smaller particle size which gives better viscosity control, body and suspension which results in a smoother feel when applying to the skin. The clay platelets form a network in water which stabilizes oil droplets in oil in water formulations. When comparing different types of clays in the lab, Elementis’ hectorite clay has proven to be the most efficient for increasing viscosity and creating better texture in formulations. The next best clay proved to be Elementis’ Magnesium Aluminium Silicate versus Bentonite and competitive Magnesium Aluminium Silicate.


Formulation examples The Hydro Light Sun Shield is an Oil in Water lotion formulation containing 1.5% Bentone Hydroclay 1100 (INCI Name: Magnesium Aluminium Silicate). This product is a vegan rheological additive based on purified smectite clay. It imparts thixotropy and good anti-settling properties in the water phase of cosmetics. It is also effective as a means of improving suspension control without unduly increasing viscosity. Furthermore, this product is an acid-stable clay and can absorb oils in skin treatments. The key benefit is an instant improvement in texture and viscosity. Those who tested this formulation considered it to be “more luxurious” than the control. The Marshmallow Melt formulation is also an Oil in Water cream that contains 1.5% Bentone Hydroclay 900, which is a combination


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of hectorite and hydroxyethylcellulose. It is a highly efficient thickener that provides significantly higher viscosity than other clay- based additives. The results are a smooth, melted marshmallow texture, as the name suggests, and the elimination of an unpleasant feel on the skin that often accompanies some SPF filters. The Maui Milk formulation is a Water in Oil


lotion that contains 7.5% of Bentone Gel HS V (INCI Name: C13-C15 Alkane, Disteardimonum Hectorite, Alcohol), which is an extremely light, more natural gel based on hemisqualane (C13- 15 alkane). This additive delivers a combination of benefits in a single, easy to use product. It is designed to impart rheological control and suspension properties to emulsion and anhydrous products. Thus, a key benefit of using this ingredient is a dramatic change in the flow profile moving from a Newtonian type flow to a very effective thixotropic flow. In our Solar Skin Frosting, Bentone Luxe WN


(INCI Name: Caprylic/Capric Triglyceride (and) Stearalkonium Hectorite (and) Polyglyceryl-3 Diisostearate (and) Polyglyceryl-3 Polyricinoleate) is used to provide rheological control with emulsification. When formulating only using emulsifiers and no clay, the solar skin frosting has no structure, and the additive gives this formulation a beautiful, light bouncy texture. The viscosity changes. Bentone Gel, an optimally dispersed


organic derivative of hectorite clay, improves formulation stability, which is key for a product like a sunscreen where performance must be superior. This gel and Luxe WN also create a network in the oil phase, but there is an added benefit of emulsification that provide a stable network with limited surfactant level for reduced irritation potential. Thermostable viscosity control is very


important in sunscreens, which can heat up to 40°C on the beach and can experience processing conditions of 80°C. Because clays are not sensitive to heat, they can offer the best heat stability and provide uniform suspension of actives regardless of temperature. Thermostability is measured using a rheometer, where chemists oscillate to measure the elastic modulus and the viscous modulus from 10-80°C. A crossover of the elastic and viscous modulus can be interpreted as potential instability when subjected to higher temperatures. Stability testing is performed to


confirm these predictions. Spray formats are incredibly popular in sun


care products. Elementis’s natural clay-based additives have thixotropy, which means they get thinner when put under higher forces, such as being forced through a spray nozzle. Achieving balance in the formulation is key to achieving sprayability. The Daily Skin Defense Lotion formulation


with Gel TN V suspends zinc oxide and titanium dioxide. Chemists altered the concentration of the Gel TN V from 0 to 8% to show how you can alter the high shear viscosity and ultimately the sprayability. This formulation was not created to be sprayed; however, product formulators will see that lower concentrations of Elementis’s natural clay-based gel have less effect on the sprayability of the formulation. This provides chemists and formulators the opportunity to “play with” the formulation. Elementis’s natural clay-based gel will also improve the stability of thinner sprays. Regarding film thickness and SPF, obviously


the thicker the film of sun cream that a person applies, then the more UV filters are sat on the skin. Elementis’s natural clay-based additives give great structure not only in the product packaging but also when applied to the skin which gives better coverage, and a thicker and continuous film. As well as film thickness, even application


is critical for sun care products as well as most skin care and makeup products. The skin is uneven and sometimes when one applies a cream, it can continue to flow and unevenly distribute itself on the skin. Elementis’s natural clay-based additives create a better structure in the product and on the skin giving even application and distribution of those important UV actives. To demonstrate this, our chemists placed


avocados on a table and applied creams with and without clay on top of them. We left them to stand for 30 minutes. The photos (Fig 3) are taken from above. After 30 minutes you can see that the cream with Hydroclay 1100 still is evenly distributed on the avocado, whereas the one without has flowed and you can see parts of the avocado through it, indicating uneven coverage. We did this again with the Daily Skin Defense


lotion with Gel TN V and the Maui Milk with Gel HS V. In both cases the coverage is much worse


Reprinted from May 2021 PERSONAL CARE


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