In the design of skincare gel formulations, silicone elastomers are widely used due to their excellent spreading properties, oil control capabilities, and skin sensation regulation abilities. A common technical question is: Can fragrance and pigments be directly added to the silicone elastomer base? And will they be quickly absorbed by the skin after application? What factors mainly affect the speed of absorption?
First, regarding the direct addition of fragrance and pigments. Theoretically, they can be directly compounded, but strict compatibility tests must be followed. The network structure of silicone elastomers is porous, and fragrance and pigment molecules need to be able to embed in its pores. If the fragrance contains high-concentration solvents of alcohols or esters, it may damage the cross-linking structure of the elastomer, causing gel collapse and water loss; pigments need to be selected that are resistant to silicon and oxidation to prevent discoloration over time. It is recommended to conduct a small-scale trial first, observing the viscosity, stability, and sensory changes of the system, before proceeding to large-scale production.
Second, the truth of the "absorption" issue. After being applied to the skin, the silicone elastomer itself will not be absorbed by the skin. It will remain in a sheet-like structure on the skin surface, forming a breathable protective film; while the small molecules of fragrance may penetrate slightly, and the large molecules of pigments will remain completely on the surface. The so-called "rapid absorption" actually refers to the spreading and deflation behavior of the silicone elastomer, rather than the penetration of substances.
Third, the core factors affecting permeation and skin sensation. 1. Molecular weight: The smaller the fragrance molecular weight, the faster the penetration rate. 2. Temperature and humidity: An increase in body temperature and high humidity will accelerate the skin's microcirculation, promoting the penetration of components. 3. Formula concentration: Excessive fragrance will increase the osmotic pressure, which may instead stimulate the skin and affect the absorption comfort.
Professional formulation development is the art of precisely controlling the balance of each component's "entry" and "retention". It is necessary to ensure the appearance level and fragrance of the product, while also safeguarding the safety and health of the skin.