Ingredient review
Bis-Stearyl PEG/PPG-8/6 SMDI Copolymer
INCI: BIS-STEARYL PEG/PPG-8/6 SMDI/PEG-400 COPOLYMER
A synthetic polymer that helps products stay put and resist water, but may feel heavy on some skin types.
In plain English
This is a man-made ingredient that forms a thin, flexible film on your skin. It helps other ingredients stick around longer and makes products more water-resistant. Think of it like a gentle, invisible glue that holds your makeup or sunscreen in place without feeling sticky.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Bis-Stearyl PEG/PPG-8/6 SMDI Copolymer is generally a lower-concern ingredient when the full formula suits your skin.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Bis-Stearyl PEG/PPG-8/6 SMDI Copolymer.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
A synthetic copolymer made by reacting stearyl alcohol with PEG/PPG chains and a diisocyanate (SMDI). It is a large molecule designed to create a flexible, water-resistant film on the skin or hair.
How it works
When applied, the copolymer dries down to form a continuous, breathable film. This film physically blocks water from washing away other ingredients and helps the product spread evenly. It also thickens the formula slightly, giving a smooth, silky feel.
Pros
Boosts water resistance
Helps sunscreens and makeup stay effective even when you sweat or get wet, so you don't have to reapply as often.
Improves wear time
Creates a flexible film that keeps foundation and eyeliner from fading or smudging throughout the day.
Cons and cautions
May feel heavy
On oily or combination skin, the film can feel slightly tacky or heavy, especially in humid weather.
Contains PEGs
PEG compounds are processed with ethylene oxide, and some consumers prefer to limit exposure to these ingredients.
Best for
- Anyone wanting long-lasting, water-resistant makeup or sunscreen
- People with normal to dry skin who enjoy a protective film feel
Use caution if
- Those with very oily or acne-prone skin who dislike a film-like sensation
Usage tips
Safety summary
Considered safe for topical use at typical concentrations. PEG derivatives have been reviewed by safety panels and are generally recognized as safe when used as directed. The polymer does not penetrate the skin.
Research notes
Limited independent studies on this specific copolymer, but the broader class of PEG/PPG copolymers and polyurethanes has been evaluated by the Cosmetic Ingredient Review (CIR) panel and found safe for cosmetic use. Most data come from manufacturer safety assessments.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the US, EU, and many other regions. No specific restrictions beyond general cosmetic safety requirements.
- Common uses
- Sunscreens, Waterproof makeup, Long-wear foundations, Eye liners
- Environmental note
- As a synthetic polymer, it is not biodegradable. However, it is used in low concentrations and is not known to bioaccumulate significantly.
Good to know
- This ingredient is not absorbed into the skin; it stays on the surface.
- It is often combined with silicones for an even silkier feel.
Common questions
What is Bis-Stearyl PEG/PPG-8/6 SMDI Copolymer in beauty products?
This is a man-made ingredient that forms a thin, flexible film on your skin. It helps other ingredients stick around longer and makes products more water-resistant. Think of it like a gentle, invisible glue that holds your makeup or sunscreen in place without feeling sticky.
What does Bis-Stearyl PEG/PPG-8/6 SMDI Copolymer do in a beauty product?
When applied, the copolymer dries down to form a continuous, breathable film. This film physically blocks water from washing away other ingredients and helps the product spread evenly. It also thickens the formula slightly, giving a smooth, silky feel.
Is Bis-Stearyl PEG/PPG-8/6 SMDI Copolymer safe for most people?
Considered safe for topical use at typical concentrations. PEG derivatives have been reviewed by safety panels and are generally recognized as safe when used as directed. The polymer does not penetrate the skin.
Who should be careful with Bis-Stearyl PEG/PPG-8/6 SMDI Copolymer?
Those with very oily or acne-prone skin who dislike a film-like sensation
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.