Isostearoyl Hydrolyzed Silk

Isostearoyl hydrolyzed silk is a derived ingredient created by chemically modifying hydrolyzed silk protein with isostearic acid. Silk protein itself comes from the cocoon of the silkworm and is composed of amino acids; hydrolysis breaks it down into smaller molecules, whilst the isostearoyl modification helps it blend seamlessly into skincare formulations.In skincare, this ingredient functions primarily as a skin conditioner. It deposits a light film onto the skin's surface, which can improve texture and tactile smoothness. Because it's derived from a natural protein source, it tends to fe…

The hydrolyzed silk component contains amino acids that can absorb onto the outer layer of skin, forming a thin, breathable conditioning film. The isostearoyl modification makes these molecules more lipophilic (fat-loving), helping them integrate with the skin's natural oils and remain on the surface longer without feeling sticky.This conditioning layer smooths micro-irregularities on the skin's surface, which can enhance light reflection and create a more refined appearance. The mechanism is largely cosmetic rather than deeply penetrative, making it suitable for most skin types.

This ingredient is typically found in lower concentrations within formulations, so it works best as part of a complete skincare routine rather than as a standalone treatment. Apply products containing it to clean skin as directed, allowing it to dry fully before layering other products. It can be used daily without concern for most skin types.

Isostearoyl hydrolyzed silk is generally well-tolerated and suitable for sensitive skin. Those with known silk allergies should exercise caution, though sensitisation is rare.