What it is
Rosin is the hard, amber-colored resin left after the volatile turpentine fraction is removed from pine or other coniferous oleoresin. In cosmetics it functions as a film former and binder that helps hold pigments together and improves the structure and adhesion of products such as lip products, sticks, and mascaras. Chemically it is composed largely of resin acids such as abietic acid and is often used in derivatized forms.
Safety & warnings
Rosin (colophony) is a well-documented contact allergen and is a common cause of allergic contact dermatitis, particularly with leave-on and lip products in sensitized individuals. People with a known colophony allergy should avoid it. Modified or hydrogenated rosin derivatives are intended to reduce, though not necessarily eliminate, this sensitizing potential.
Origin & sourcing
Natural, plant-derived. It is the non-volatile residue obtained from the oleoresin of pine and related conifer trees after distilling off the turpentine.
History
Rosin, also called colophony, has been used for centuries in applications ranging from varnishes and adhesives to treating violin bows, and its film-forming resin acids carried over into use in cosmetics and personal-care products.
Questions everyone asks
What does rosin do in a lip or stick product?
It acts as a film former and binder, helping hold pigments together and giving the product structure, adhesion, and gloss.
Is rosin an allergen?
Yes. Rosin, also called colophony, is a recognized contact allergen and a known cause of allergic contact dermatitis in sensitized people.