The HEMA Hiding Inside “HEMA-Free” Gels
A gel can be labelled "HEMA-free" and still contain HEMA. Acrylates Copolymer — the backbone of most HEMA-free gels — can be manufactured from HEMA, and residual unreacted HEMA can stay trapped inside it.
- INCI rules require only the copolymer name on the label, not the monomers used to build it.
- Residual unreacted HEMA can remain at levels of up to 15%.
- When researchers lab-tested 37 nail products against their labels, every product containing acrylates showed a discrepancy.
In Part 1 we named the monomers that replace Hydroxyethyl Methacrylate (HEMA). This part is about the ingredient sitting above all of them on the label — and the gap in the labelling rules that sits underneath it.
What is Acrylates Copolymer?
Scan the ingredient list of almost any leading HEMA-free gel polish and you will find Acrylates Copolymer near the top. Brands sometimes present it as the safe, inert alternative to reactive monomers.
That is not quite accurate.
Acrylates Copolymer is a broad INCI term covering a wide range of pre-formed polymers and oligomers. The key word is pre-formed. These are not free reactive monomers looking for something to bond to — they are already polymerised structures that give the gel its backbone.
If reactive monomers are individual LEGO bricks loose in the box, Acrylates Copolymer is a section already clicked together at the factory. A big pre-built section is far less likely to end up somewhere it shouldn't. But you still need loose bricks to join the sections to each other — and to the nail. A gel built purely on pre-formed copolymer would not cure.
So Acrylates Copolymer is the structural backbone. It is not a functional replacement for reactive monomers, and any brand implying otherwise is either confused or hoping you are.
The part the industry rarely discusses
Acrylates Copolymer can itself be synthesised from HEMA.
HEMA is one of several monomers routinely used as a building block in the polymerisation process that creates these copolymers — precisely because it is cheap and such an effective adhesion promoter. The other monomers in the blend might be HPMA, Di-HEMA derivatives or IBOA. But HEMA remains a frequent starting material.
And polymerisation is never 100% complete. It never is, in any chemical process.
Residual unreacted HEMA can remain trapped inside the copolymer at levels of up to 15%.
Under INCI rules, only the copolymer name goes on the ingredient list — not the monomers used to build it. A product can therefore print "Acrylates Copolymer", legally claim to be HEMA-free, and still carry meaningful unreacted HEMA inside that copolymer. Nothing on the label will tell you.
This matters most with product from lower-cost OEM factories, where there is a direct commercial incentive to use HEMA in the copolymer synthesis — and less rigorous control over residual monomer levels.
This is not theoretical
In 2023, researchers at the Finnish Institute of Occupational Health put 37 gel and acrylic nail products through gas chromatography–mass spectrometry and compared the results against the labels.
Every single product that contained (meth)acrylates showed a discrepancy between what was declared and what was in the bottle.
- HEMA was found in 20 of the 37 products — and many packages did not declare it.
- IBOA turned up in nine gel products and was declared on none of them.
A separate 2023 survey of 394 nail cosmetics found HEMA present in nearly 60% of products, mandatory warning labels missing on more than 30%, and outright mislabelling on around 10%.
Those are two independent teams reaching the same conclusion from different directions: the ingredient list is a starting point, not a guarantee.
What this means on Monday morning
It does not mean you should throw everything away and panic. It means the "HEMA-free" claim on the front of a bottle is worth exactly as much as the quality control of the factory that made it — and no more.
Which raises the obvious question: who actually made your gel? That is Part 3.
Common questions
Can a product labelled HEMA-free still contain HEMA?
Yes. Acrylates Copolymer can be synthesised from HEMA and residual unreacted HEMA can remain trapped inside it at levels of up to 15%. INCI rules require only the copolymer name on the label. Independent laboratory analysis has repeatedly found (meth)acrylates in nail products that were not declared on the packaging.
Is Acrylates Copolymer safe?
As a pre-formed polymer it does not carry the same direct sensitisation risk as free small monomers, because large pre-polymerised structures do not cross skin easily. The concern is not the copolymer itself — it is what may be left over inside it from how it was made.
The HEMA-Free series
- Part 1 — What actually replaces HEMA
- Part 2 — The HEMA hiding inside "HEMA-free" (you are here)
- Part 3 — Why so many gels feel identical
- Part 4 — It is not the ingredient, it is the cure
- Part 5 — How to judge a gel system
Related reading: Can you trust your gel polish ingredient list?
References
- Suuronen K, et al. Acrylates in artificial nails — results of product analyses and glove penetration studies. Contact Dermatitis, 2024 (online 14 December 2023). Finnish Institute of Occupational Health. PubMed 38093646
- Steunebrink IM, et al. Presence of 2-hydroxyethyl methacrylate (HEMA) and other (meth)acrylates in nail cosmetics, and compliance with EU legislation: an online market survey. Contact Dermatitis, 2024. PubMed 37848187
- Regulation (EC) No 1223/2009 on cosmetic products (consolidated text). eur-lex.europa.eu
Not sure what is really in your products? Email help@ikoniqnails.com, WhatsApp +49 160 649 7218, or use our contact form.
Written by Robert Giblett, Founder & CEO of IKON.IQ®.
