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Glass is used extensively in our everyday lives. It’s used in windows, mirrors and other items like glasses and other homeware pieces. To the untrained eye, it all appears exactly the same. Even though all glass looks the same, it doesn’t mean it actually is. In fact, there have been many different types of glass used in the past. One of the most modern, particularly for use in window applications, is float glass. If you are completely new to float glass, then you’ve come to the right place as we are going to discuss what it is, how it differs from other glass and hopefully give you a better overview of float glass manufacture.

What is Float Glass?

Float glass is the type of glass used in most modern windows and sash windows. It is a distortion-free and very smooth form of glass that is made using a method often referred to as the Pilkington Process, after the Pilkington brothers who are credited with inventing it.

How is Float Glass Manufactured?

Float glass manufacture takes place by taking molten glass in a furnace and pouring it into a special chamber that has been lined with a layer of molten tin. Under strict conditions, when the molten glass is poured onto the tin, it starts to float on top and takes the shape of that particular container. It can be spread to a width of between 90 and 140-inches and to a thickness that has been predetermined in the design stages.

The upper and lower surfaces of the resulting glass are called the score (or air) side and the tin side respectively. While the air/score side is fire-polished, the lower surface is not. The shaped glass is then taken out of the chamber and into a type of oven known as lehr. Within the lehr it is then cooled very slowly at a constant rate.

This part of the process is known as annealing and reduces any internal stresses the glass may be experiencing. The cooling rate is very important and can determine the quality of the finished product. When the glass is finally taken from the lehr it is at room temperature.

Automatic cutters are then used to trim the edges to finish it off neatly and cut the glass to the desired length.

Why It Replaced Plate Glass

In the past, plate glass was the most widely used glass. That form of glass was made with a time-consuming and hazardous process that involved a lot of polishing and grinding. Float glass manufacture replaced it not only because of the already specified reasons but that it was more dangerous to handle when it was broken and is not nearly as energy efficient as float glass.

So, next time you are looking out of the window, you will now know a little more about the process that was involved in making it. Take a look at our double glazing page for more information on our glass.

Enjoy being warm and comfortable!

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