Ingredient review
Butanediol/TMDI/IPDI Copolymer
INCI: BIS-POLY(1,4-BUTANEDIOL)-9/TMDI/IPDI COPOLYMER
A synthetic film former that helps makeup last longer and resist water, but may feel tight or dry on sensitive skin.
In plain English
This is a man-made polymer (a type of plastic) that forms a flexible, invisible film on your skin or lashes. It helps makeup stay put through sweat, humidity, and tears, and is commonly found in long-wear foundations, waterproof mascaras, and lip stains. Think of it as a clear, breathable shield that locks your look in place.
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
Butanediol/TMDI/IPDI 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 Butanediol/TMDI/IPDI 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 created by reacting butanediol with two types of diisocyanates (TMDI and IPDI). It belongs to the polyurethane family and is designed to form a durable, flexible film on the skin or hair.
How it works
When applied, the copolymer's molecules link together as the solvent evaporates, creating a continuous, water-resistant film. This film physically holds pigments and other ingredients in place, reducing transfer, smudging, and fading. It also helps ingredients adhere to the skin for longer wear.
Pros
Exceptional wear time
Creates a durable film that keeps makeup intact for 12+ hours, even in humid or sweaty conditions.
Water and smudge resistance
Helps mascara and eyeliner resist tears, rain, and rubbing, reducing the need for touch-ups.
Cons and cautions
Can feel tight or dry
The film-forming nature may cause a stiff or drying sensation on sensitive or dry skin, especially around the eyes.
Requires double cleansing
Water-resistant films don't break down with water alone; you'll need an oil-based or micellar cleanser to remove it fully.
Best for
- People who want long-wearing, transfer-resistant makeup
- Those with oily or combination skin who struggle with makeup fading
Use caution if
- Individuals with very dry or dehydrated skin who find film formers uncomfortable
- Anyone who prefers minimal, easily removable makeup
Usage tips
Safety summary
Considered safe for topical use at typical concentrations. The polymer is fully reacted and does not release free isocyanates. Rare reports of mild irritation in very sensitive individuals, but overall low risk.
Research notes
Limited independent studies on this specific copolymer, but the broader polyurethane family is well-studied and widely used in cosmetics. Safety assessments by the Cosmetic Ingredient Review (CIR) have found polyurethane film formers to be safe as used.
Common label clues
- Typical concentration
- 1–10% in leave-on products
- Regulatory status
- Approved for use in cosmetics in the EU, US, and other major markets. The individual monomers (TMDI, IPDI) are used in fully reacted form and are not present in the final product at harmful levels.
- Common uses
- Long-wear foundations, Waterproof mascaras, Lip products, Eyeliners
- Environmental note
- As a synthetic polymer, it is not biodegradable and may contribute to microplastic pollution. Some brands are moving toward bio-based alternatives.
Good to know
- This ingredient is often listed under the broader category 'Polyurethane' on some labels.
- It is not the same as polyurethane foam used in furniture—cosmetic-grade polymers are safe for topical use.
Common questions
What is Butanediol/TMDI/IPDI Copolymer in beauty products?
This is a man-made polymer (a type of plastic) that forms a flexible, invisible film on your skin or lashes. It helps makeup stay put through sweat, humidity, and tears, and is commonly found in long-wear foundations, waterproof mascaras, and lip stains. Think of it as a clear, breathable shield that locks your look in place.
What does Butanediol/TMDI/IPDI Copolymer do in a beauty product?
When applied, the copolymer's molecules link together as the solvent evaporates, creating a continuous, water-resistant film. This film physically holds pigments and other ingredients in place, reducing transfer, smudging, and fading. It also helps ingredients adhere to the skin for longer wear.
Is Butanediol/TMDI/IPDI Copolymer safe for most people?
Considered safe for topical use at typical concentrations. The polymer is fully reacted and does not release free isocyanates. Rare reports of mild irritation in very sensitive individuals, but overall low risk.
Who should be careful with Butanediol/TMDI/IPDI Copolymer?
Individuals with very dry or dehydrated skin who find film formers uncomfortable Anyone who prefers minimal, easily removable makeup
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.