Optical Mechanism of the Soft-Focus Effect
Silica (silicon dioxide) achieves a visual soft-focus effect through its porous, micron-sized particle structure, with the core principle being diffuse reflection and scattering of light. When light shines on the skin surface, microscopic irregularities such as pores and fine lines create shadows, making imperfections more visible. Silica powder distributes evenly within the skin's texture, scattering incident light in a non-specular manner, causing the light to diffuse evenly at multiple angles, creating a soft, even illumination effect similar to a "shadowless lamp." This visually blurs imperfections, evens skin tone, and achieves a natural, "airbrushed" makeup look. This process does not rely on pigment coverage but is achieved through physical optical modulation, resulting in a lightweight, breathable makeup effect that does not clog pores.

Physical Adsorption Mechanism of Oil Control
Silica possesses an ultra-high specific surface area (up to 200–400 m²/g) and a rich nanometer-scale microporous structure, efficiently capturing sebum through physical adsorption. Its surface is rich in hydroxyl groups (–OH) and siloxane bonds, which, through surface tension and van der Waals forces, act like "microscopic sponges" to adsorb and fix excess facial oil, significantly reducing shine in the T-zone. Some studies indicate that its surface functional groups may also participate in weak chemical adsorption, further enhancing oil fixation. This process does not interfere with sebaceous gland secretion, acting only on surface free oils, achieving a balanced oil control effect of "absorbing oil without drying out the skin."

Core Application Examples and Formulation Design
Silica is widely used in oil-controlling setting powders, matte foundations, and setting sprays as a core functional filler. Taking Carslan Black Magnetic Loose Powder as an example, its formula uses 8-micron high-purity fumed silica, resulting in an ultra-fine powder with a "smoke-like" texture, achieving:

Instant oil absorption: Absorbs sebum within 3 seconds of application, transforming oily shine into a matte finish;
Soft-focus and blurring effect: Fills in pores and fine lines, minimizing acne marks and redness;
Long-lasting and sweat-proof: Treated with hydrophobic and oleophobic surface treatment, forming a breathable and invisible film to resist mask friction and high-temperature environments;
Skin-friendly and nourishing: Contains moisturizing ingredients to prevent dryness and tightness caused by traditional oil-control products.
This ingredient is also used in high-end foundation liquids as an "invisible support structure," improving powder fluidity and film stability.
International Scientific Support and Cutting-Edge Technology
The soft-focus function of silica has been incorporated into the patent system in the international cosmetics science field. US patent US2005/0118220 clearly states that non-porous spherical silica particles (particle size 1–100 μm) added to cosmetics in a proportion of 0.1–70% can achieve a significant soft-focus effect. Other research has explored encapsulating liquid oils (such as jojoba oil) with porous hollow silica microspheres to create stable water-based formulations, expanding its application potential in sustained-release cosmetics and functional skincare products.