Seeing the opportunities for real in thin glass tempering

The glass industry globally is buzzing with talk about the opportunities of thin glass. And the advantages seem perfectly clear. All the players in the value chain are demanding exactly what thin glass excels at providing: lighter, cheaper, and ultimately higher-quality glass that enable more efficient and sustainable solutions for end customers. So why hasn’t thin glass already caught on like wildfire?

With all the growth drivers pushing for thin glass, it is amazing that there are still a limited number of solutions and actual real-life cases where very thin heat-treated glass is used.

Thin glass reduces the costs of freight, installation and raw materials, and even helps lower transportation emissions. Thin glass efficiency and low weight are ideal for solar, architecture and automotive applications. Plus, thin glass provides a range of new products for glass processors, including vacuum insulated glazing (VIG), fire-resistant glass (FRG) and cold-bent facades for more intriguing, radical forms of architecture.

The thinnest commonly available heat-treated glass today is 3 mm, although the market is looking towards even thinner solutions of around 2 mm. Yet a major hurdle is that only about 12% of the tempering lines available in Europe today can provide such thin heat-treated glass. So, there is an overall lack of capacity to produce such thin glass. Why?

The cost of thin raw glass

Float glass manufacturing, which is at the start of the glass value chain, has been tuned to produce tons of end product. Therefore, the float glass process has been designed to produce thicknesses between 4 mm and 19 mm. Existing float glass plants are able to handle thinner glass, even down to 2 mm, but then the output in tons is significantly reduced.

This poses the first obstacle for the development of the thin glass business. And currently, the price of the thin float glass is more expensive than 4 mm glass, for example, thereby slowing down the development especially of high-volume applications.

Thin 2 mm fully tempered glass

Thin glass processing is a challenge

The existing thin glass heat treatment and tempering process, too, causes another obstacle, since it has been designed for the commonly used thicknesses of 4 to 19 mm.

The tempering process has two important parameters that affect the glass tempering: 1. The glass exit temperature when it leaves the furnace and 2. The quenching pressure. The higher the temperature of glass, the lower the quenching pressure needs to be. The problem, however, is the extreme drop in viscosity as the soft glass is transported on rollers from the heating zone into the quenching zone, which causes optical distortion. This is especially problematic for architectural applications, which aim to eliminate glass distortion and iridescence.

Although 3 mm technology already exists today, 2 mm  glass tempering has been impractical and excessively expensive. A very limited number of viable solutions are currently available that can actually handle thin glass while keeping the quality high. Advanced technology is essential to overcome those challenges and provide glass processors with feasible opportunities to match the market’s dreams.

Thin glass tempering with GlastonAir at Glaston ShowroomImage: Launched in 2013, the GlastonAir™ flat glass tempering furnace by Glaston represents a significant breakthrough to temper very thin glass. To get a better idea of how the technology works and what kinds of end results are possible for specific applications, GlastonAir™ is available at the Glaston Showroom in Finland for test purposes.

Future of thin glass

Tempered thin glass is proven to be ultra flexible and more robust, so it will continue to play a bigger role in future applications. While development in technology is inevitable, the requirements for thin glass are expected to become even more complicated. Solar panel manufacturers, for example, will start to require glass from 1.6 mm to 2.2 mm in their search for better panel efficiency, while architects will ask for even lighter solutions with increased insulation performance.

Opportunities are only just unfolding for thin glass at the moment. What is hindering the development most is the lack of processing capability, although proven and commercially viable solutions like GlastonAir™ already exist. In the end, it is only a matter of time before thin glass moves mainstream and allows the world to experience the immense benefits of its presence.

You can find more about the thin glass applications and opportunities in this summary of GPD Finland 2015 technology presentation:

GDP Finland Technology

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About the author

Miika Äppelqvist

Encourages transparent solutions in buildings and ways of working. Seven years of experience from being a glass-man in product management, sales and projects with a focus on glass heat treatment. Believes helping is the best marketing any company can do. Father of two toddlers and a wannabe sportsman with an internal love of ice hockey.