Sericin is a protein found on the surface of silk strands-- it is the molecular glue that binds the raw strands together. This protein is also used in cosmetics to smooth and help hydrate skin and as an additive in some fine papers.

Ser"i*cin (?), n. [L. sericus silken.] Chem.

A gelatinous nitrogenous material extracted from crude silk and other similar fiber by boiling water; -- called also silk gelatin.

© Webster 1913.