Paul Cartlidge* outlines how Fenzi’s E-Coat technology, which eliminates the need for edge deletion or post-enamel coating, improves the performance and design flexibility of coated glass.
Coated glass has become a cornerstone in both the architectural and automotive industries, offering enhanced performance, aesthetics, and energy efficiency.
These coatings are created by applying microscopically thin layers of metals or metal oxides – such as silver (Ag), tin oxide (SnO₂), zinc oxide (ZnO), and titanium dioxide (TiO₂) – to the glass surface.
By carefully designing the composition and thickness of these layers, manufacturers can alter the glass’s optical and thermal properties. These multilayer stacks are engineered to regulate light transmission, minimise heat gain or loss, and improve durability, making coated glass essential in modern glazing systems.
Architectural applications
In architecture, coated glass is integral to sustainable building design. Among the most widely used variants are low-emissivity (Low-E) coatings.
These coatings reflect infrared radiation while allowing visible light to pass through, thereby reducing heat transfer. This thermal control helps maintain consistent indoor temperatures, decreasing reliance on HVAC systems and significantly lowering energy consumption.
Low-E coatings also mitigate solar heat gain, reduce glare, and enhance occupant comfort. They are commonly used in commercial buildings, high-rise structures, and green-certified developments to meet stringent energy codes and environmental standards.
Beyond thermal performance, architectural coatings can be tailored for additional functionalities such as: colour tinting for aesthetic appeal, privacy enhancement, and UV protection, and self-cleaning surfaces.
These features expand the versatility of coated glass in both residential and commercial applications.
Automotive applications
In the automotive sector, coated glass enhances safety, comfort, and energy efficiency.
Windshields and side windows often feature solar control coatings that reduce cabin heat and block harmful UV rays – improving passenger comfort and protecting interior materials from fading.
Automotive glass may incorporate both IR-reflective and Low-E coatings to block unwanted solar energy; minimise heat loss; stabilise interior temperatures; reduce air conditioning load; and improve fuel efficiency.
In electric vehicles, these benefits contribute to extended battery range – an increasingly critical factor in EV design.
Advanced coatings also support technologies such as head-up displays (HUDs), embedded sensors, and driver-assistance systems.
These applications require high optical clarity and minimal reflection, which coated glass provides.
Coating technologies
Coated glass is typically manufactured using two primary methods:
- Pyrolytic (hard coat): applied during the float glass production process, hard coats are highly durable and suitable for single glazing or exterior surfaces.
- Magnetron Sputtering (soft coat): applied in vacuum chambers, soft coats offer superior performance but require protection through lamination or double glazing.
Each method has its advantages, depending on the intended application and performance requirements.
Sustainability
From a sustainability standpoint, coated glass plays a vital role in reducing energy consumption and carbon emissions.
In buildings, it enhances thermal insulation and solar control, contributing to certifications such as Leadership in Energy and Environmental Design (LEED) and Building Research Establishment Environmental Assessment Method (BREEAM).
In vehicles, it supports compliance with fuel efficiency and emissions regulations.
Edge deletion
Edge deletion is a critical step in the fabrication of insulating glass units (IGUs) that use coated glass. This process involves removing a narrow strip of the coating around the perimeter of the glass pane.
Though seemingly minor, edge deletion is essential for ensuring the long-term performance and durability of high-performance glazing systems.
Soft coatings, such as those applied via magnetron sputtering, are sensitive to environmental exposure. When used in IGUs, the edges of the glass are sealed with adhesives and spacers to create an airtight cavity.
If the coating is not removed from these edges, it can compromise the seal due to poor adhesion, moisture-induced corrosion, and/or reduced thermal performance and lifespan.
Edge deletion ensures that sealants bond directly to bare glass, preserving the integrity of the IGU. This process is typically performed using mechanical abrasion, lasers, or chemical treatments, and must be carefully controlled to avoid damaging the glass or leaving residues.
Glass enamels can be used after edge deletion, to improve aesthetics of the glazing unit and hide building features.
Figure 1 - E-Coat Technology Process.
Edge considerations
In automotive glazing, most glass components require edge treatment using obscuration enamel. This black enamel is screen or digitally printed around the perimeter of the glass before bending. During the firing process, the enamel becomes an opaque, chemically resistant band.
This enamel serves several purposes:
- Conceals adhesives used to bond the glass to the vehicle frame.
- Protects adhesives from UV degradation.
- Enhances the visual appeal of the vehicle.
A major challenge in printing conventional obscuration enamels onto coated glass is that these enamels were not originally formulated for the surface chemistries of modern coatings. When applied, the glass enamels can react with the metals and oxide layers in the multilayer stack.
The nature of this reaction depends on the enamel’s composition, the processing conditions, and the layers of metal and metal oxide that comprise the stack. These interactions can result in delamination, poor adhesion, undesirable visual effects, and an unpredictable lifespan under real-world conditions.
Solutions
To address these challenges, manufacturers can:
- Remove the coating on cut-size glass before enamel application (edge deletion).
- Apply soft coatings after enamel printing, which requires precise process control and access to coating equipment.
While specialised enamels have been developed to accept soft coatings, it remains much more economical to coat jumbo sized glass.
Etching enamel technology
A promising solution in this field is etching enamel technology, which allows enamel to be applied directly over coated glass. This approach eliminates the need for edge deletion or post-enamel coating.
The key lies in a specially formulated enamel that chemically etches the coating, bonds directly to the underlying glass, maintains high physical strength, colour fidelity, and opacity, and provides a robust surface for adhesive bonding.
One such patented technology developed by Fenzi is E-Coat (Fig 1), which is gaining traction in the architectural sector and is currently being tested in the automotive industry.
These enamels contain reactive glass particles that selectively etch the coating and form a molecular bond with the substrate.
The chemistry is tuneable to accommodate different coating stacks and can be incorporated into screen printing pastes or digital inks.
Conclusion
Coated glass continues to drive innovation in both architectural and automotive sectors. From energy efficiency and occupant comfort to advanced digital integration, its applications are vast and growing.
As technologies like etching enamels evolve, the industry moves closer to seamless, cost-effective solutions that enhance both performance and design flexibility.
*Marketing Manager, Fenzi Advanced Glass Technologies (AGT), Milano, Italy
