In cosmetics, fumed silica as a filler needs to meet some specific requirements. The following are the characteristics of common fumed silica as a cosmetic filler:

Fine particle size: When fumed silica is used as a filler, it usually needs to have a fine particle size, usually on the nanoscale or submicron scale. Such a fine particle size allows it to be evenly dispersed in cosmetics without creating a harsh feeling in the product.

High specific surface area: When fumed silica is used as a filler, it is an important feature to have a high specific surface area. High specific surface area means that each unit mass of fumed silica has more surfaces for filling, which can more effectively fill fine lines, pores and other tiny depressions on the skin surface.

Transparency: As a cosmetic filler, fumed silica needs to have good transparency. It should not affect the color or transparency of cosmetics to ensure the appearance and texture of the product.

Lightweight texture: The purpose of fillers is to fill in depressions in the skin's surface, but they also need to have a lightweight texture. A good filler should provide a soft, smooth feel so that the product does not feel heavy or sticky when applied to the skin.

Good adhesion: When fumed silica is used as a filler, it needs to have good adhesion to ensure that it can evenly adhere to the skin surface and maintain a long-lasting effect.

It should be noted that the use of fillers in cosmetics should be adjusted and controlled according to specific product needs and regulatory requirements. When choosing and using cosmetic products, it is recommended to refer to product instructions, consult a professional, and follow appropriate directions and recommendations for use.