TPO (trimethylbenzoyl-diphenylphosphine oxide), known as Trimethylbenzoyl-diphenylphosphine oxide in English, is a fundamental organic molecule in the world of nail art. With the molecular formula C₂₂H₂₁O₂P, TPO belongs to the family of photoinitiators and has been widely used in UV/LED nail gels and some photo-curable resins. Its main role is to activate under UV or LED light, releasing free radicals that trigger the polymerization process, transforming the gel from liquid to solid in a few seconds.
The Introduction of TPO in the Nail Industry
The arrival of TPO in the nail world coincided with a technological turning point: in 2005, the first LED lamps were introduced, which were faster and more efficient than traditional UV lamps. However, the most commonly used photoinitiator until then, camphorquinone, did not work well with this new technology. In 2008, TPO emerged as a valid alternative, thanks to its high reactivity to LED light (wavelength 400-405 nm), its transparency which does not alter the color of the gel, and a reduced sensation of heat ("burning") during polymerization. Initially, TPO had some limitations, including high costs and the need for balanced formulations to avoid skin irritation.
The Evolution of LED-Only Gels with TPO
Between 2010 and 2012, some innovative brands began to produce gels exclusively compatible with LED lamps, adopting TPO as the main photoinitiator. These products were intended for advanced beauty salons and professional techniques that required high performance. The market enthusiastically embraced the faster polymerization and aesthetic quality, although there remained some concern about possible irritations caused by incomplete polymerization.
PRR Gels: Rapid Polymerization and Guaranteed Quality
In 2015, PRR (Polymerization Rapid Reaction) gels were born, a new category characterized by rapid polymerization (between 30 and 60 seconds), a shiny and transparent surface, and perfect compatibility with modern LED lamps. Thanks to TPO, these gels gradually began to replace camphorquinone, especially in clear, builder, and light cover gels.
Problems in the Nail Industry Before TPO
Before the widespread use of TPO, between 2014 and 2016, the nail industry was characterized by many difficulties. Professionals often had to deal with gels that ran, remained sticky, or did not cure properly. The nail surfaces were too hard or brittle, and the results were often inconsistent even when using quality products. These problems were caused by immature formulations, ineffective photoinitiators, unreactive monomers, and poor-quality LED lamps. Many criticisms spread in online communities, especially towards low-cost brands, accused of selling unreliable products.
The Boom of TPO and HEMA in 2016
In 2016, the market stabilized thanks to the widespread introduction of two key ingredients: TPO and HEMA. TPO, a powerful photoinitiator, guaranteed rapid and uniform polymerization even with low-end LED lamps, effectively and economically curing dense and pigmented gels. HEMA, a reactive and adhesive monomer, improved adhesion, workability, and gel durability. This combination leveled the quality between high-end and low-cost products, leading to the spread of many brands also aimed at a non-professional audience. This led to the tendency to mix products from different brands, with the belief that "they all work."
The Ban of TPO in Europe: What Changes from September 1, 2025
Starting from September 1, 2025, TPO will be banned throughout the European Union under Regulation (EU) 2023/1545, which classifies it as a CMR substance (mutagenic and toxic for reproduction). This means it can no longer be used in any cosmetic product, including nail gels. HEMA, already subject to restrictions in several countries for its allergenic potential, is also increasingly under observation by European authorities.
TPO: Why It's Not Always Harmful
It's important to clarify that TPO is not inherently harmful: the risk depends on the usage methods and the degree of polymerization.
In professional settings, with correctly formulated products and complete polymerization, the risk is significantly reduced. In qualified salons, certified and powerful lamps are used, and operators are trained to minimize direct contact with unpolymerized product, always working safely.
During polymerization, the TPO molecule (Trimethylbenzoyl-diphenylphosphine oxide) absorbs UV/LED light energy and cleaves, generating free radicals that initiate the cross-linking reaction of monomers. Once polymerization is complete, TPO is no longer active: its function is finished, and the molecule transforms into stable and chemically inactive compounds, incorporated within the solid gel structure.
For this reason, if the product is polymerized correctly, the presence of TPO does not pose significant risks to either the client or the nail technician.
Problems mainly arise from:
- use of inadequate or too weak lamps,
- insufficient polymerization times,
- excessive or uneven product application.
The Risk of TPO in Home Use
The main problem arises when products containing TPO are used at home without adequate training and with cheap or low-performance LED lamps. In these cases, polymerization is often incomplete, leaving active residues on the skin or nails, which can cause irritation, contact allergies, and, in more severe cases, respiratory problems.
Nailover's Conscious Choice: Safety and Innovation
In a context where many brands only adapt to regulations when they become mandatory, Nailover has chosen a different path: anticipating changes to ensure safety, quality, and innovation.
Why Nailover is a High-End Brand
Nailover is a professional brand, intended exclusively for use in salons and by qualified nail technicians.
High End means top-tier: superior quality products, balanced formulas, selected raw materials, and rigorous controls on every production batch. It is not a low-cost DIY product, but a line designed for those who want to work with maximum safety, reliability, and performance.
Perfect also for students who, from the very beginning, want to have access to the best in the nail industry.
Our TPO-Free Timeline
- From 2022 → We invest in research and development to reformulate products without TPO, introducing new TPO-Free formulas.
- June 2, 2025 → The European Union publishes the ban on TPO use in salons in the Official Journal, effective September 1, 2025.
- July 15, 2025 → Nailover becomes the first company in Italy to sell only TPO-Free products, anticipating the regulatory deadline.
- July 2 – August 31, 2025 → We notify all customers well in advance and support them in organizing the complete transition to 100% TPO-Free.
- September 1, 2025 → Official effective date of the ban: Nailover is already fully compliant weeks ahead.
What Will Change for Low-Cost Brands?
The TPO ban represents a major challenge for many economic brands that rely on third-party manufacturers without directly controlling their formulas. These brands often lack internal laboratories or qualified technical staff. Adapting to the new regulations will require a complete reformulation of products, the use of safer but also more expensive ingredients, and finding a balance between safety and performance. Not all will be able to face this challenge seriously.
Nailover: Guarantee of Quality and Safety
At Nailover, we have anticipated the times by developing 100% TPO-Free and 95% HEMA-Free formulas, guaranteeing professional performance and compatibility with the most modern LED lamps. All our products are designed and controlled entirely in Italy at every stage of the production process.
Conclusion: Safety Is Not a Compromise
In an evolving market, safety is not improvised. Many chase after existing regulations, but those who work seriously can make a different choice, today. Choosing Nailover means choosing a safe, compliant, and professional path for your salon and for your clients.
With Nailover, your salon is already compliant. Without risks. Without compromises.
