PFAS coating replacement: qualifying fluorine-free alternatives

A fluorine-free replacement for a PFAS coating should be qualified against the coating’s actual job, substrate and service conditions. Water repellency, oil repellency, ice adhesion, transparency and durability are different properties. A laboratory result for one does not establish the others, and eliminating fluorinated ingredients does not automatically establish suitability for food contact, medical use or every chemical requirement.

The PFAS coating function and candidate replacement

Qualifying a replacement for a coating containing PFAS (per- and polyfluoroalkyl substances) begins with the function that causes the customer to specify the existing treatment. A surface used to shed rain has different requirements from one exposed to lubricants, cleaning chemicals or repeated icing. Record the relevant liquids, temperatures, contact times and appearance limits. This prevents a substitution project from accepting an impressive but irrelevant water-contact-angle result while losing the property that made the original treatment useful.

A 2025 study by Mandal and colleagues provides a concrete research example: a waterborne polyurethane and metal-organic-framework coating, followed by treatment with fluorine-free alkyl silanes. The paper reports liquid-repellent behaviour, transparency and laboratory robustness. Its value is a demonstrated material design that can be investigated for applications. It does not establish a qualified drop-in replacement for every PFAS coating, substrate or industrial line.

Repellency measurements and durability after exposure

The words used to describe repellency need precise measurements. A droplet may bead on a surface yet remain strongly pinned to it. Static contact angle, sliding behaviour and the difference between advancing and receding angles describe different aspects of liquid interaction. For a self-cleaning or drainage application, the ability to move contamination away can matter more than the appearance of a stationary droplet. Measure the liquids and contamination relevant to the product rather than select a test fluid because it produces a favourable image.

Durability should preserve the required function after exposure, not simply leave the coating visible. Abrasion, ultraviolet light, thermal cycling, detergents and impact can act together in service. A water-jet demonstration probes a particular damage mechanism; it cannot predict every combination of outdoor ageing and cleaning. The acceptance programme should check the useful surface property after the relevant exposures and establish how failures appear, including local damage, adhesion loss or gradual deterioration.

Application control and formulation consistency

Substrate preparation and application control can change the outcome. Surface cleanliness, roughness, formulation stability, coating thickness and curing conditions should be reproduced on representative production parts. A formulation described as sprayable still needs evidence about transfer efficiency, edge coverage, drying, rework and waste. Waterborne chemistry can alter the line’s drying load or corrosion considerations. Compatibility with an existing spray booth is therefore a question to test rather than a capital-saving assumption.

The laboratory formulation must also become a dependable supply. Particle size and distribution, raw-material variation, dispersion stability and storage life can influence coating performance. A manufacturing batch should retain its useful properties after shipping and the normal interval before application. The UCL laboratory’s publication record identifies the research context of the example; buyers still need a supplier specification and responsibility for commercial consistency if the formulation is offered as a product.

Composition evidence and cost over the service life

Composition claims require evidence at the level at which they are made. Establish what the supplier means by fluorine-free or PFAS-free and the documentation or testing used to support it. Assess the other constituents and the intended use separately. A change that removes one chemical family can still introduce migration, emissions, degradation or exposure questions. Medical suitability and food-contact acceptance require their own application evidence and cannot be inferred from a transparent, water-based or non-fluorinated formulation.

The commercial decision rests on service delivered over time. Compare coating material, application, inspection, rejected parts, cleaning and replacement against the existing treatment under the same requirements. A slightly less impressive initial property may be acceptable if it remains sufficient for longer or simplifies maintenance. Conversely, a low-cost treatment can be expensive if it requires frequent renewal. Qualification is complete only for the defined product and operating envelope, with change control for the formulation and application process.