By Shawn Lim, Head of R&D
We didn’t start out with a grand plan to disrupt an industry. FibreCoat is the product of an intuition – an intuition that if a functional coating could be applied at the exact point in glass-fibre production where every filament exists on its own, many later steps might simply become unnecessary. What followed was a total reconsideration of fibre-coating. And the result was a filament-first coating method: a way to coat metals or polymers directly onto individual glass fibres during spinning, creating a hybrid material with new properties and radically different economics.
Starting with how glass fibre is actually made
Glass fibre production is already one of the most refined high-volume manufacturing processes in modern industry. Raw materials, supplied as powders, are blended into a precise composition and melted in a furnace at temperatures above 1,200°C. The molten glass flows into a platinum-rhodium bushing which is electrically heated to maintain the narrow viscosity window required for fibre formation.
From there, the glass passes through thousands of nozzles, each producing a single filament with a diameter typically between 7 and 22 microns. These filaments are thinner than a human hair and extremely sensitive. If the viscosity is too low, the glass drips. If it is too high, fibre tension increases and filaments break. One break causes a chain reaction that forces the entire process to stop for manual intervention.
Immediately after formation, a sizing is applied. This aqueous chemical formulation protects the filaments from abrasion and tailors their compatibility with downstream processes and matrices. Sizing chemistry is not an afterthought; it largely determines how fibres behave in weaving, chopping, winding, or dispersion. In conventional glass fibre manufacturing, sizing recipes are closely guarded secrets, as distinctive as a fingerprint.
Once sized, the filaments are gathered into yarns and wound at speeds of 25 to 35 metres per second. The genius of this process is not the raw material cost – glass itself is cheap – but the speed, scale, and consistency with which it can be produced. This is why glass fibres account for the overwhelming majority of composite reinforcement volume worldwide.
The overlooked opportunity
Here is the opportunity. The economics of the glass fibre industry are built on volume and velocity; our key insight was that this very efficiency could be exploited rather than replaced. Glass fibre already provides mechanical strength and processability. The coating is where additional functionality lives.
In conventional approaches, functional coatings are applied after fibres are bundled into rovings or yarns. To coat at the filament level, manufacturers must first re-separate those fibres, using mechanical or pneumatic methods that are slow, energy-intensive, and often damaging. Performance is lost before functionality is even added.
Our approach intervenes earlier. By positioning a coating module between fibre formation and sizing, we apply the coating at the only point in the process where every filament is naturally separated. No re-spreading is required. Each filament is coated individually, then reunited into a yarn that still behaves like a textile.
This seemingly small change has big consequences. It ensures that every filament carries the hybrid properties of the material. It preserves textile processability. It also opens the door to filament-level polymer impregnation, effectively turning the yarn itself into a composite rather than merely a reinforcement.
Hybrid fibres, not metal imitations
The coatings we apply are thin, continuous sheaths of metal or polymer. Aluminium is the primary metallic coating, chosen for its low melting point of 660°C, high electrical conductivity, and strong electromagnetic interference shielding, all at minimal added weight.
Under a microscope, the structure is unambiguous: a glass core that provides strength, flexibility, and scalability, surrounded by a metallic shell that delivers functionality. This hybrid morphology is fundamentally different from pure metal fibres.
Metal fibres are typically produced by bundling metal rods and drawing them repeatedly through dies. The process is slow, capital-intensive, and expensive. At comparable diameters, pure metal fibres can cost more than €1,000 per kilogram. By contrast, our coated glass fibres can be produced at an order of magnitude lower cost, because they ride on the back of an already optimised industrial process.
Proving the idea at the smallest scale
The journey from insight to industry began slowly. Our first proof-of-concept experiments were conducted on lab-scale spinning lines, working with single filaments and small molten-metal applicators. Line speeds of around 300 metres per minute were far below industrial norms, but sufficient to answer the core question: can a continuous, uniform metallic coating be applied to a moving glass filament without disrupting fibre formation?
Even at this scale, the challenges were non-trivial. The aluminium had to be kept molten well above 700°C, with stable temperature control. The interaction between glass and metal had to promote wetting and adhesion without embrittlement. And the entire system had to fit within the tight spatial envelope of a spinning line.
Success at this stage was about control.
Scaling without starting from scratch
In advanced materials, scaling is often assumed to require greenfield plants and vast capital expenditure. We chose a different path. Rather than building an entirely new production line, we designed our technology to integrate into existing glass fibre spinning infrastructure.
This decision forced discipline. Existing lines come with fixed geometries, interfaces, and operational constraints defined by decades-old equipment. Molten-metal handling technology, meanwhile, is usually designed for heavy industry, with furnaces holding tonnes of material. We needed crucibles holding just a few kilograms of aluminium, capable of high power density, precise temperature control, and continuous operation alongside molten glass.
No off-the-shelf solution existed. We developed our coating modules from the ground up, researching high-temperature heating concepts, technical ceramics, refractory materials, and sensor systems compact enough for our needs. Progress was rarely linear. Many development cycles ended with cracked ceramics or molten aluminium where it was not supposed to be. Each failure, however, clarified the constraints of the system and told us where we had to improve.
Industrial reality sets the rules
A major step forward came through partnership with Deutsche Basalt Faser, which gave us access to full-scale industrial spinning lines. For the first time, our modules could be tested under real production conditions, with industrial winders, operators, and safety requirements.
At this stage, safety became as important as performance. The process brings molten glass at over 1,200°C and molten aluminium above 700°C into close proximity. Equipment design had to prioritise containment, stability, and operator protection, while remaining compliant with industrial standards.
The result is a modular spinning line concept with integrated coating, eliminating the need for a dedicated glass furnace. These modules can be packaged, shipped, and deployed with comparatively low capital investment, making advanced fibre production more accessible.
Chemistry comes back into the picture
Coating the fibres changed their surface fundamentally, which meant sizing chemistry had to be rethought as well. Traditional sizings are formulated for bare glass. Our fibres present both metallic and glass surfaces, each with different chemical behaviours.
To enable weaving, chopping, or dispersion into chaff, new sizing formulations were required. Developing them pushed us into another domain entirely: applied chemistry. This was not optional. Without compatible sizing, even the most advanced fibre remains unusable in practice.
Why the process matters
Our work is often described in terms of materials, but its deeper significance lies in process engineering. By intervening at the exact moment when each filament is exposed, we can create functional fibres without the cost and complexity of post-processing.
The real achievement is not the coating itself, but making it work reliably, safely, and economically within an industry that changes slowly and operates at enormous scale. We did not replace the glass fibre industry, but learned how to work inside it.
As we expand into new coating materials and serve sectors ranging from defence and space to construction and consumer electronics, the underlying principle remains the same. Innovation does not always require new factories or new supply chains. Sometimes it requires looking closely at an existing process and asking, very precisely, where is the one moment we can change everything?