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How is glass made?

Man working with hot glass

Glass is one of those things that has become such a regular feature of our everyday lives that we tend to take it for granted.

In our homes, workplaces, cars, electronic equipment and appliances, glass has many applications. This blog will anser the question – How is glass made? You will have a better appreciation and understanding of one of the most common synthetic materials we rely on each day.

The history of glass making

Glass is often thought of as an invention of modern man, but ancient civilisations have a long history of creating more primitive versions of glass products for thousands of years.

The first evidence of human attempts to make glass date back to around 3500 BC, in Egypt and parts of Mesopotamia. Glass became more useful in tools and vessels around 1500 BC as the process for production became more refined. Due to the basic tools being used, and the inability to create sufficient heat, ancient glassmaking was inefficient and difficult.

The invention of glassblowing allowed for more useful and artistic applications of the finished product. Vases, glasses and other ornaments can be masterfully created by literally blowing air through a specially designed pipe to expand and manipulate the liquid glass before it hardens.

Modern glass making is largely automated and done by machinery for commercial productivity. Although the equipment and techniques have come along way since the first versions of glass making, the core processes remain largely the same.

Materials and machinery used for glass making


The demand for high-quality glass means the production process has become very refined.

Glass is typically comprised of a variety of elements that are combined and heated to extremely high temperatures to create the finished product. The primary ingredient in glass is silicon dioxide, which is commonly found in nature in materials such as quartz.

You may have heard of glass being made from sand; this is because silicon dioxide (also known as silica) is the primary constituent in sand. Combined with limestone, sodium carbonate and a handful of minor additions, this forms the basic recipe for the glass you see in your homes and workplaces.

Machinery and Process

It is difficult to imagine how a composite of minerals and elements can be transformed into a sturdy, transparent pane of window glass. Although the equipment and processes are much more advanced these days, the fundamental rules to glass making still apply.

The real magic happens via the chemical reactions that occur in the heating process.

When the mineral compound (let’s call it the “sand” for simplicity) is added to a specially designed glass furnace and heated to around 1700°C. At this point, the sand actually begins to change state from a solid, into an amorphous liquid which is like a hot, syrupy goo!

This liquid can then be poured into moulds or ‘floated’ on a flatbed to produce perfectly level sheets, suitable for windows. A cooling process then hardens the liquid back to what we now recognise as a typical glass product ready for use.

Different types of glass

To create different types of glass, additional steps are added into the basic process to achieve slightly different looks.

How is Stained Glass

To create the stunning visual appeal of stained glass, specific metal oxides and powders can be added whilst the glass is in it’s liquid form. Strips of the stained glass are then held in place with a steel frames to form a larger window or door.

Hardened or Tempered Glass

By cooling the liquid glass at a faster rate than usual, glassmakers add extra strength to the finished glass. If it does break, it will typically shatter differently, forming non-jagged crumbs which are less dangerous in an accident.

From ancient civilisations right up to 21st century applications, glass has been an integral part of society, commerce and shelter. From a few simple ingredients and bit of cool chemistry, the finished product is created for a variety of uses around the world every day and it would be hard to imagine a world without glass.

Need custom glass made for your home or workplace? Talk to the glass experts at Koala Glass and let us take care of the entire installation process. Get in touch on (02) 4968 1450 today.


Image source: Pixabay

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