Polyester-8

Polyester-8 is a synthetic film-forming polymer used in cosmetics at low percentages (typically ~0.1–5%) to improve wear and texture, and it is generally considered biologically inert with minimal skin penetration. Clinical irritation risk is low, but as an occlusive/film former it can rarely provoke stinging or frictional irritation on severely compromised barriers (e.g., active eczema or post-procedure skin), so it is not scored as completely inert. Safety Notes: Polyester-8 is most commonly used as a film-forming/hold polymer in OTC hair-styling and cosmetic leave-on products (gels, sprays, mousses, mascaras), where it can appear at low “supporting” levels around 0.05–0.3% in multi-polymer systems to boost hold and humidity resistance. In high-hold consumer styling gels and strong-hold sprays, it has been observed used as a primary structuring resin in the low single-digits up to about 8%, with higher levels limited by viscosity, tack/flake risk, and solubility/clarity in the chosen solvent system. Rinse-off usage is less common and typically lower because deposition is limited and high levels can impair rinse feel, so the upper end is driven by leave-on styling formats.