What it is
Hydrolyzed silk is made by hydrolyzing the fibroin protein of silk into smaller peptides and free amino acids so that it dissolves readily in water-based formulas. In sunscreens and other leave-on products it leaves a smooth, conditioned feel on skin and can form a light surface film that improves sensory finish. It is used at low concentrations primarily for its skin-feel and moisture-binding properties rather than for any active function.
Safety & warnings
Hydrolyzed silk is generally well tolerated in cosmetic use. Because it is a hydrolyzed protein, sensitization is possible in rare cases, and people with a known allergy to silk should be cautious. It is animal-derived, so it is not suitable for those avoiding animal-sourced ingredients.
Origin & sourcing
Animal-derived. The starting material is silk fibroin obtained from the cocoons of the silkworm Bombyx mori, which is then chemically or enzymatically hydrolyzed into a peptide and amino acid mixture.
Questions everyone asks
Is hydrolyzed silk vegan?
No. It is derived from silkworm cocoons, so it is an animal-sourced ingredient and not considered vegan.
What does hydrolyzed silk do in a sunscreen?
It acts mainly as a conditioning and humectant agent, helping the formula feel smooth and leaving a soft finish on the skin.