Benefits of Natural Clay-Based Ingredients in Sun Care Formulations

Benefits of Natural Clay-Based Ingredients in Sunscreen Formulations As awareness grows that skin requires protection not only while sunbathing at the beach but throughout the day, sunscreen products are no longer seasonal items and are now used intensively in daily care routines worldwide. Formulators developing effective sunscreen products must follow global health trends and recognize growing consumer demand for sustainable, environmentally friendly raw materials that offer benefits including UV protection, ease of application, smooth skin feel, instant radiance, tanning, and moisturization. Three key trends in sunscreen products have emerged in recent years.

Health-Focused Products

Consumers wish to use sunscreen products made from natural raw materials that meet their health needs, such as broad-spectrum sun protection for skin cancer prevention and anti-aging benefits. We use sunscreen to protect our skin from UVB rays that cause tanning and sunburn in the epidermis, and also from UVA rays that penetrate deeper into the dermis and cause skin damage such as wrinkles; as is known, UV damage can lead to skin cancer.

'Green' and Environmentally Friendly Products

Consumers across all personal care market segments focus on clean, environmentally friendly, and sustainable products, and therefore when it comes to suncare, they continue to believe natural products are safer for themselves and the environment. Consumers are becoming familiar with natural additives such as clay that enhance the effectiveness of mineral and safe organic UV filters. Multifunctional Products Focused on Sensory Experience and Personalization Consumers demand easy-to-apply innovative structures that transition from foam, gel, or cream to powder formulations. Multifunctional hybrid suncare products are suitable for daily use and are becoming an indispensable part of regular skin health and beauty care regimens. Sunscreen products are generally offered in oil-based formulations and various forms such as sprays, balms, lotions, and creams. Products in this structure generally have high water resistance. Stick-type products typically contain no water and are quite effective because most UV filters are oil-soluble ingredients. Transparent sprays have the advantages of easy application and fast protection. Additionally, water-based formulas have begun to spread in the personal care sector. Although this formula type makes it difficult to achieve high SPF in suncare products, it provides a lighter feel than oil-based formulas and, thanks to better moisturizing properties, offers consumers a better moisturizing and anti-aging product. [caption id="attachment_135144" align="aligncenter"] Clay Concentration in Water Figure 1: Concentration Curve[/caption]

Why Are Natural Clays Effective?

Natural clay-based additives help capture trends by improving sensory experiences in the formulas they enter in the following ways: • Ensuring effective retention of organic and inorganic sun-protective active ingredients and effect pigments, • Increasing SPF to provide better skin protection in both organic and inorganic sunscreen formulations, • Increasing water resistance for beach and sports products, • Capturing natural and clean ingredient product and market trends, • Offering different sensory experiences with different product structures. [caption id="attachment_135145" align="aligncenter"] Figure 2: Spray Formulation Images[/caption] From premium to mass-market brands, many manufacturers benefit from the advantages of natural clay in suncare products. Clays have a network-forming property in formulas. Within this network, clay keeps particles suspended, ensuring the resulting product is stable and homogeneous. Clays produced by Elementis generally have smaller particle size compared to clays on the market. Smectite clay raw material plays an important role for formulators in developing formulas that leave a good feel on the skin and in various textures. Hectorite, due to its large surface area and uniform charge distribution, is one of the most effective rheological agents in the smectite clay family. Elementis owns a hectorite mine in California in the western region of the United States. Bentone Hydroclay, a hectorite clay additive developed by Elementis under a vegan and COSMOS-approved trade name, has a smaller particle size and therefore provides better viscosity control, consistency, and suspension, giving a smoother feel when applied to skin. Clay platelets form a network in water, stabilizing oil droplets in water-based formulations. When different clay types are compared in the laboratory, Elementis' hectorite clay has been proven to be the most effective clay in increasing viscosity and creating better texture in formulations. In comparison with Bentonite and Magnesium Aluminum Silicate, the second most effective clay was proven to be Elementis' product Magnesium Aluminum Silicate.

Formulation Examples

The Hydro Light Sun Shield is a water-based lotion formula containing 1.5% Bentone Hydroclay 1100 (INCI: Magnesium Aluminum Silicate). Bentone Hydroclay 1100 is a vegan rheological additive containing purified smectite clay. It imparts thixotropic and anti-settling properties to the aqueous phase of cosmetic products. It is also effective as a suspension improvement agent without unnecessarily increasing viscosity. This product also has oil-absorption properties in skin care applications, but its primary benefit is its immediate improvement of feel, texture, and viscosity. Test subjects evaluated the formulation containing this raw material as having "a more luxurious feel" compared to the control group. Marshmallow Melt is a water-based cream formula containing 1.5% Bentone Hydroclay 900 (a mixture of hectorite and hydroxyethylcellulose). Bentone Hydroclay 900 is a very effective thickener that provides significantly more viscosity compared to other clay-based additives. As the name suggests, when the product is applied, it imparts a unique texture to the skin resembling melted marshmallow and does not cause an uncomfortable feel like some SPF filters can. Maui Milk is an oil-based lotion containing 7.5% Bentone Gel HS V (INCI: C13-C15 Alkane, Disteardimonum Hectorite, Alcohol), a very light, more natural gel based on hemisqualene (INCI: C13-15 alkane). This ingredient combines numerous benefits in a single, easy-to-use product. It is designed to impart rheology control and suspension properties to emulsions and anhydrous formulas. Therefore, one of the main benefits of using this ingredient is the ability to vary the rheology profile over a wide range (from Newtonian to thixotropic flow). The Solar Skin Frosting formula uses Bentone Luxe WN (INCI: Caprylic/Capric Triglyceride, Stearalkonium Hectorite, Polyglyceryl-3 Diisostearate, Polyglyceryl-3 Polyricinoleate) to rheologically control the emulsion. The structure of Solar Skin Frosting cannot be achieved when formulated using only emulsifier without clay; the clay additive gives this formula a beautiful, light, and vibrant texture and thus changes viscosity. Bentone Gel, an organic hectorite clay derivative showing optimal distribution, has the property of increasing formula stability, which is quite important for sunscreen products expected to deliver superior performance. Bentone Gel and Luxe WN products, while forming a network in the oil phase, have another important benefit: they create a stable network with limited surfactant content, thereby reducing irritation potential. Thermostable viscosity control is very important in sunscreens exposed to temperatures reaching 40°C and even 80°C following intense exposure at beaches. Since clays are not heat-sensitive, they can provide the best thermal stability regardless of temperature and ensure homogeneous distribution of active ingredients. Thermostability is measured using a rheometer set between 10-80°C to measure elastic modulus and viscous modulus. Crossover of elastic and viscous modulus can be interpreted as potential instability when exposed to higher temperatures. Stability testing is performed to confirm these predictions. Spray-type products appear very commonly in sunscreen formulations. Elementis' natural clay-based additives are thixotropic, meaning they thin under high shear (during spray dispensing). Achieving balance in the formulation is very important in terms of sprayability performance. The Daily Skin Defense Lotion formula contains Bentone Gel TN V and has Zinc Oxide and Titanium Dioxide suspended in its content. Formulators increased Gel TN V concentration from 0% to 8% to demonstrate high shear viscosity and how sprayability performance changes as a result. Although this formulation was not designed for spray application, formulators will observe that low natural clay-based gel concentrations have less effect on the formulation's sprayability performance. This way, they will have the opportunity to "play" with the formulation; natural clay-based gel will also increase the stability of finer sprays. Regarding film thickness and SPF, it is clear that the thicker the applied sunscreen film, the more UV filters adhere to the skin. Elementis natural clay-based additives not only give the product a perfect structure but also form a thicker and continuous film when applied, providing better skin coverage. Beyond film thickness, application is also very important for suncare, skincare, and makeup products. Since skin is not smooth, sometimes when a cream is applied, it can continue to flow on the skin and distribute unevenly. Elementis natural clay-based additives ensure these important UV active ingredients are applied and distributed evenly, providing better structure to the product and skin. To demonstrate this, avocados were placed on a table and creams with and without clay were applied to them. The avocados were left for 30 minutes and then photographed from above (Figure 3). After 30 minutes, the cream containing Hydroclay 1100 was observed to distribute more evenly on the avocado, while the cream without it flowed and did not distribute evenly on the avocado. This test was repeated with Daily Skin Defense Lotion containing Gel TN V and Maui Milk containing Gel HS V. In both cases, formulations without clay showed worse coating performance after 30 minutes. Particularly in experiments with Maui Milk, the formulation without clay completely disappeared on the avocado. For formulations containing Luxe WN, the same results were obtained as with formulations without clay but containing emulsifier. [caption id="attachment_135146" align="aligncenter"] Figure 3: Avocado Test Images[/caption]

Testing SPF Enhancement Effects: Scientific and Creative Approaches!

The combination of rheology, application, and stability is expected to help us achieve the SPF enhancement objective. Some in vitro test results are as follows: Elementis chemists also applied sunscreen to a glass slide and measured the contact angle of a water droplet on it to learn how advanced film structure and integrity can affect product hydrophobicity. A high contact angle means water sits better on the film, while a low angle means it spreads more. Formulations with contact angles above 30°C may indicate hydrophobicity. Since Hydroclay products are water-based thickeners and do not affect product hydrophobicity, our chemists did not include data on them. The Daily Skin Defense Lotion formula containing Gel TN V increased the contact angle of the water droplet by 20%, while the Maui Milk formula containing Gel HS V provided approximately 60% increase in contact angle. All Elementis natural clay-based gel-free formulations, since they contain only gel components without clay, can observe the pure effect of clay rather than oil in the gel. Similarly, the UV Blocking Protector formula containing Luxe WN achieved 90% increase in contact angle and Solar Skin Frosting achieved the same enhancement effect with six times higher contact angle. Elementis chemists wanted to demonstrate SPF enhancement properties in real-world conditions and conducted initial testing using a foot spa to assess water resistance in vivo. Sunscreen was applied to subjects' feet, waited 20 minutes, then kept in turbulent foot spa for 40 minutes. Photos were then taken of the sunscreen-treated feet. After the subject's foot was immersed in the foot spa, looking at the samples showing Daily Skin Defense lotion (Figure 4), it is clear that Elementis natural clay-based gel remained on the foot. In general, this product does not leave white traces when properly applied to skin; however, this was done for visual effect purposes here. [caption id="attachment_135147" align="aligncenter"] Figure 4: In Vitro Test Images[/caption] In the test with Maui Milk, after washing, you can see how much better the sample containing Gel HS V was compared to the clay-free example and how much lotion was lost in the clay-free sample.

Conclusion

Natural clays offer numerous benefits to consumers seeking suncare products that consider current market trends and deliver promising sun protection performance. By combining diverse clay contents, formulators can create effective, luxurious-feeling, and highly stable formulas.

Translator/Editor: Özge Yüksel Özel

Authors:

Kate Watermann Global Product Development & Technical Support Manager, Personal Care Elementis Global

Christina Schenatzky Application Specialist, Personal Care Elementis Global

Valentin Burzynski Global Manager, Applied Research Elementis Global

Kim Burch Global Technical Director, Consumer Group Elementis Global