Polyethylene Terephthalate

What is Polyethylene Terephthalate?

Polyethylene terephthalate (PET) is a synthetic thermoplastic polyester created through the condensation reaction of ethylene glycol and terephthalic acid, resulting in a strong, lightweight polymer. In cosmetics, it takes the form of microspheres, fibers, or thin films, distinct from its packaging applications. Primarily featured in long-wear foundations, mascaras, hair sprays, sunscreens, and nail polishes, PET works by depositing a sheer, flexible layer on skin, hair, or nails. This sheath boosts product performance by preventing smudging, repelling moisture, and locking in color or style. As a binding and adhesive component, it unites formula elements for better cohesion and spreadability, while its viscosity adjustment ensures smooth, stable textures ideal for application.

Comedogenic Rating 0/5 Low risk of clogging pores
EWG Safety Rating 1 View on EWG →

Roles in Formulation

This ingredient serves the following purposes in cosmetic formulations:

Adhesive
Improves adhesion so the product or film sticks to skin, hair, or nails; helps bind layers together in patches, nail products, and long-wear formulas.
Film former
Creates a continuous film on skin or hair to improve wear, water resistance, transfer resistance, shine, or hold in sunscreens, makeup, and styling products.
Hair fixative
Provides style hold by forming a film on hair, helping maintain shape, reduce frizz, and improve durability in sprays, gels, and mousses.
Viscosity controlling agent
Adjusts thickness to the desired level for stability and usability, improving dispensing, suspension, and texture across many formulation types.
Binding
Provides cohesion by helping ingredients stick together, improving the strength and integrity of pressed powders, tablets, or solid bars.

Benefits

Delivers extended wear and transfer resistance for makeup and sunscreens.

Provides firm hold and smoothness in hair styling aids like sprays and gels.

Enhances nail product adhesion and texture for lasting finishes.

Who It's For

A quick guide for who this ingredient may suit (and who should be cautious).

Who May Benefit Who Should Avoid
Users wanting makeup that withstands sweat and humidity.
Those preferring fully natural or plant-based ingredients.
People styling hair for all-day volume and frizz control.
People concerned about petroleum-derived synthetics.
Individuals applying nail formulas needing durability and shine.
Individuals wary of surface films on very dry or tight skin.

Safety Notes

  • Functions as an inert surface agent with low skin penetration risk.
  • Non-comedogenic profile supports use across skin types.

Frequently Asked Questions about Polyethylene Terephthalate

What makes PET useful in cosmetics?

It forms protective films for better adherence, water resistance, and product stability.

Is polyethylene terephthalate irritating?

Evidence points to low irritation potential in typical cosmetic concentrations.

Can PET be used around eyes or on sensitive areas?

Yes, its inert nature supports inclusion in eye-area and general skincare products.