Ingredient review
Glycerin/Isophthalic Acid Copolymer Castorate
INCI: GLYCERIN/ISOPHTHALIC ACID COPOLYMER CASTORATE
A gentle film-forming ingredient that helps products stay put and resist water, but offers no direct skincare benefit.
In plain English
This ingredient is a type of polymer (a long-chain molecule) made by combining glycerin, isophthalic acid, and castor oil. In a cosmetic product, it dries down to form a thin, flexible film on your skin or hair. This film helps other ingredients stay in place longer and makes the product more resistant to water and sweat. Think of it like a clear, breathable shield that doesn't feel heavy or 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
- semi synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Glycerin/Isophthalic Acid Copolymer Castorate 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 Glycerin/Isophthalic Acid Copolymer Castorate.
- 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 semi-synthetic copolymer created by reacting glycerin, isophthalic acid, and castor oil. It belongs to a class of ingredients called polyesters and is designed to form a durable yet flexible film.
How it works
When applied, the copolymer molecules spread out and link together as the solvent (usually water or alcohol) evaporates. This creates a continuous, invisible film that adheres to the skin or hair surface. The castor oil component gives the film flexibility, so it moves with your skin without cracking or feeling tight.
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.
Flexible feel
Unlike some film-formers that can feel stiff or mask-like, the castor oil component keeps the film pliable and comfortable on skin.
Cons and cautions
No active skincare benefit
This ingredient only forms a film; it doesn't hydrate, soothe, or treat skin conditions on its own.
Potential tightness
In high concentrations or on very dry skin, the film might create a slight pulling sensation, though this is rare at typical use levels.
Best for
- Anyone wanting longer-lasting makeup or sunscreen
- People who swim or sweat and need water-resistant products
Use caution if
- Those who prefer minimal-ingredient routines and avoid film-formers
Usage tips
Safety summary
Glycerin/Isophthalic Acid Copolymer Castorate has a low irritation and sensitization profile. It is not known to be comedogenic and is considered safe for most skin types at typical use levels.
Research notes
While not extensively studied in isolation, the individual components (glycerin, isophthalic acid, castor oil) are well-established as safe in cosmetics. The copolymer itself is accepted by industry safety panels based on its chemistry and low reactivity.
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 known restrictions at typical concentrations.
- Common uses
- Water-resistant sunscreens, Long-wear makeup, Hair styling products, Moisturizers
- Environmental note
- As a synthetic polymer, it may not be readily biodegradable. However, its environmental impact is considered low due to the small amounts used in rinse-off and leave-on products.
Good to know
- This ingredient is often used in combination with other film-formers to fine-tune the feel and durability of a product.
- It is considered safe for use in cosmetics by major regulatory bodies, including the U.S. Cosmetic Ingredient Review panel.
Common questions
What is Glycerin/Isophthalic Acid Copolymer Castorate in beauty products?
This ingredient is a type of polymer (a long-chain molecule) made by combining glycerin, isophthalic acid, and castor oil. In a cosmetic product, it dries down to form a thin, flexible film on your skin or hair. This film helps other ingredients stay in place longer and makes the product more resistant to water and sweat. Think of it like a clear, breathable shield that doesn't feel heavy or sticky.
What does Glycerin/Isophthalic Acid Copolymer Castorate do in a beauty product?
When applied, the copolymer molecules spread out and link together as the solvent (usually water or alcohol) evaporates. This creates a continuous, invisible film that adheres to the skin or hair surface. The castor oil component gives the film flexibility, so it moves with your skin without cracking or feeling tight.
Is Glycerin/Isophthalic Acid Copolymer Castorate safe for most people?
Glycerin/Isophthalic Acid Copolymer Castorate has a low irritation and sensitization profile. It is not known to be comedogenic and is considered safe for most skin types at typical use levels.
Who should be careful with Glycerin/Isophthalic Acid Copolymer Castorate?
Those who prefer minimal-ingredient routines and avoid film-formers
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.