How Mirrors are Made

Mirror, mirror on the wall… And the car. And inside TV. And pretty much everywhere else. You’d be hard pressed to get through a day without them, but how are mirrors made? And how were mirrors made in the past? Let’s take a look.

Engineering How It’s Made
1 July 2022

Try, if you will, to reflect for a moment on the prospect of a world without mirrors. Fun houses wouldn’t be quite as fun. Discos wouldn’t have their glittering balls. And nobody’s eyebrows would ever be anywhere near fleek, never mind on it.

As for how mirrors are made, this has come a long way since the copper and bronze versions of the Egyptians, Greeks and Romans. So, how were mirrors made in the past? And how are mirrors made in factories today?

How were Mirrors made in the Past?

Garden room with antique mirror (Photo: Mint Images via Getty Images)

Mirrors have been around for centuries, and their history is a fascinating one. But how were mirrors made in the past?

The first mirrors were made from polished metals and were used to reflect light or objects. The earliest mirrors were usually just curved pieces of highly polished metal, such as brass or bronze. In time, though, mirrors expanded from being mere tools to becoming works of art and symbols of wealth and luxury.

The mirrors of ancient Rome were made of highly polished metal, usually bronze. They were generally quite small, only about six inches in diameter, and were used to check one’s appearance before going out. Some mirrors had a handle for carrying them around. Most mirrors were decorated with intricate designs, often featuring scenes from mythology or everyday life. Some were even made of gold or silver. They were often given as presents or wedding gifts.

In terms of “how were mirrors made in the past” it was in the 14th century that the first glass mirrors were produced in the city of Venice. The Venetians produced simple glass mirrors that reflected off a metal backing; they later perfected this technique using a combination of tin and mercury.

Eventually the secret of mirror making spread to other cities. By 1835 a German chemist developed the silver-backed method that paved the way for how mirrors are made today.

How are Mirrors Made Today?

Distorted Reflection on Building Facade (Photo: Michael Lee via Getty Images)

To answer the question “how are mirrors manufactured”, we must begin with what they are made from. A variety of materials are used in mirror making. The most popular is glass, but they can also be made from plastic, metal, and other materials.

Glass mirrors are made by coating a glass surface with a thin layer of metal. The most common metals used for this purpose are silver and aluminium. Silver is used to produce mirrors that are high in quality and reflectivity, while aluminium is used to produce mirrors that are less expensive.

How are Mirrors Made from Glass?

View from a car wing mirror (Photo: mikroman6 via Getty Images)

The actual process of creating a glass mirror is a complex one that begins with the selection of the right type of glass. Once this has been chosen, the mirror maker must determine the thickness of the glass and cut it to size. The next step is to apply a thin layer of the selected metal – usually silver or aluminium – to one side of the glass. This process, known as silvering, is what will create the reflective surface of the mirror. For more complex shapes, the answer to how mirrors are made is that they are created by blowing molten glass into a pre-set mould. The mould itself is created by casting molten metal into a mould made from plaster or other material.

How are Mirrors Produced in a Factory?

Mirror Mirror! (Photo: Marianna Massey via Getty Images)

When mirrors are produced in a factory, the basic process is scaled up to an industrial, and heavily automated, scale.

Initially, the factory will utilise large clear panels of glass as the core element of mirror production. A robot places each panel horizontally on a conveyor belt that takes the panel to a washing station. Here, powerful jets spray the glass with water and a cleaning and polishing agent, cerium oxide. During this stage, swiftly rotating brushes clean and polish both the top and bottom surfaces of the glass to remove any contaminants from the glass.

Finally, powerful jets of hot demineralized water will wash down the glass to leave it completely clean and ready for the next step in the mirror production process.

How are Mirrors Manufactured? Silvering

Once the glass is clean and ready, it’s time for the silvering process. As stated above, this is where metal is added to the glass, but how does this translate in terms of how mirrors are manufactured? In industrial production, the first metal that’s usually applied is liquefied tin, which goes on the back of the mirror.

This tin layer is used as a base to make ready for the second – and crucial – metal layer to be applied, usually silver or aluminium. During this process liquid silver is mixed with a chemical activator and hardens within seconds. It’s this silver layer that transforms the clear glass into a mirror.

To complete the process, the mirror is usually sealed with a copper layer, paned and dried. The completed mirror will pass through an oven to seal and dry it. Finally, an acid wash is used to remove any metal residue that may remain.

How are Mirrors Produced in a Factory? Cutting and Shaping

The factory can now cut these large mirror panels to create a variety of shapes and sizes using a special mirror cutting machine. This is a precision guided tool that’s controlled by highly specialised computer software.

The machine cuts and shapes the mirror using a specialised hardened metal cutting wheel. Round mirrors are also made in this way, whereby the machine will first cut the mirror panel into squares, with the circle then cut inside each square.

For more specialist mirror production, it’s usually the case that the mirror factories will ship whole panels to specialist producers, who will undertake the cutting process themselves.

And that’s the mirror making process. From “how were mirrors made in the past” to how mirrors are made today, including “how are mirrors produced in a factory”, we’ve looked at the question of “how are mirrors made” from all angles.


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