My Science School

 

 

 

What have a window, a light bulb and a firefighter’s clothes got in common? They are all made from glass! This amazing material is all around you. It comes in lots of different shapes and sizes.

 

 

 

 

 

 

Glass is a very useful material.

Glass has many special features. Light can shine through glass and you can see through it. It is smooth and colourless. Glass does not let water through – it is waterproof. Glass does not rot or turn rusty. It’s easy to make smudges or marks on glass, but it is also easy to clean!

 

 

Continue reading "What is glass?"

 

 

Most of the glass that we use is made in a factory. It is made from a mix of sand and other materials. When the mixture is heated, it turns into a thick liquid that looks like see-through treacle. The hot liquid cools down and turns into hard glass.

 

 

 

 

 

Glass is made from natural materials.

Glass is made from natural materials – sand, soda and lime. These materials are cheap and plentiful, and found all over the world. They are dug out, or quarried, from the ground. Other materials are sometimes used to make certain types of glass. However, sand is usually the main ingredient.

 

 

 

 

 

Other materials are added to make special types of glass.

Adding other ingredients to the basic glass mixture makes different types of glass. Coloured glass is made when different chemicals are added to the glass mixture. Thin wires are sandwiched inside a cooling glass mixture to make wire glass which is very strong.

 

 

 

 

 

Some natural glass is found in the Earth.

Natural glass forms in the mouth of a volcano. The heat of the volcano melts sand and other materials to form natural glass, called obsidian. This glass was first used by humans to make very sharp tips for spears!

 

Each type of glass is made in a different way. A piece of very thin glass is made in a different way from a strong glass bottle. The liquid glass may be cooled down quickly or slowly to make different kinds of glass. Glass can be shaped in many ways.

 

 

 

 

Flat, clear glass is called ‘float glass’.

In a factory, ingredients are measured and mixed and then heated up in a furnace (hot oven). As the mixture cools, it is shaped. To make glass for a window, the glass mix is spread over hot liquid metal. It is called float glass because it floats on the liquid metal. The contact between the glass and the metal is perfectly flat.

 

 

 

 

 

 

 

Glass is shaped when the mix is still runny and hot.

Glass cools quickly so it needs to be shaped before it sets and hardens. Glass can be shaped either by craft workers or special machines.

 

 

 

 

This bottle was shaped by a mould.

Liquid glass is poured into a mould. As it cools down, air is forced in to make the hollow. The glass hardens and is taken out of the mould.

 

 

 

 

 

 

 

Glass-making is skilled work.

Glass ornaments are often made by heating, joining and shaping several pieces of glass.

You can blow glass up like blowing up a balloon!

 

 

 

 

 

Glass is useful because it keeps the wind and rain out but let’s in light. Glass is naturally transparent. This means you can see through it. Glass can be made in beautiful colours. Glass can also be made cloudy so that you can’t see through it.

 

 

 

 

 

 

 

Glass is easy to see through.

Transparent glass is used everywhere, from windows to the glasses that people wear to help them see clearly. In the past, some windows were so thick that it was difficult to see through them! Thick glass is less clear than thin glass. Glass that only allows some light to pass through is called translucent.

 

 

 

 

 

 

 

 

You can’t see through some glass!

Some glass only allows through a small amount of light. This cloudy glass is called opaque. It is used when people don’t want others to see in. Opaque glass is often used on front doors or in bathroom windows.

 

 

 

 

 

 

You can make your own stained glass window!

Collect some coloured sweet wrappers. Ask an adult to help you cut a window frame from black card. Use black sticky tape to stick the wrappers in the window. Put your frame on a windowsill and see the colours as the Sun shines through!

 

Imagine your house without glass – it would be very dark with no windows or light bulbs! Today, glass is used for many things from lights to camera lenses. It is even used to make material for clothes. Here we look at ways in which glass helps us.

 

 

 

 

 

 

Catseyes in the road shine in the dark.

 In the dark, tiny lights mark out the direction of the road. These lights are made from glass and metal beads. When light from a car shines on them, they reflect the light back and mark the shape of the road. The lights are called Catseyes because they shine in the dark like the eyes of a real cat.

 

 

Continue reading "Helpful glass"

 

 

If you knock a light bulb it will shatter into tiny pieces. Glass can be very weak or very strong. Some glass shatters easily but glass can also be made strong enough to survive fierce knocks, wild winds and heavy hailstones!

 

 

 

 

 

 

This glass does not fly around when it is smashed.

Laminated glass is made like a sandwich with two layers of glass and a plastic filling. If laminated glass breaks, the pieces of glass stick to the plastic instead of flying around. This kind of glass is used on car windscreens for safety.

 

 

 

This canoe is partly made from glass.

Glass reinforced plastic is strong and hard. It is made by sandwiching glass fibre between layers of plastic. It can be easily shaped and is used to make builders’ hard hats, boats and the bodies of some cars and aeroplanes.

 

 

 

 

 

 

This rocket has a glass nose!

When a space rocket blasts into space, it gets extremely hot. Many materials crack at such temperatures. A special glass called glass-ceramic can survive these temperatures without damage. The tops of most electrical ovens are now made of glass-ceramic. Glass-ceramic was actually discovered when glass was overheated by mistake!

 

 

 

 

 

Glass can keep heat inside a building. A glass greenhouse lets in the Sun’s heat to help plants grow. Double glazing can help to keep a house warm. A layer of fiberglass padding can be put in the loft or attic of a house. It keeps the house warn in winter.

 

 

 

 

 

 

 

Some glass does not crack when heated.

The glass in this lantern is heat-resistant. You may have heat-resistant glass jugs, bowls or dishes in your kitchen. Ordinary glass cracks and breaks if boiling water is poured in or put over heat. Glass made with a special chemical does not break when heated. This is useful for glass cooking pots.

 

 

 

 

 

 

 

 

Mirrored windows help save energy.

Mirrored glass reflects a lot of the Sun’s rays and can stop buildings in hot countries from getting too hot. Double glazing and fiberglass are used to keep houses cool in hot weather and warm in cold weather.

 

 

 

 

 

 

 

A thermos flask keeps your drink hot or cold.

Glass is used inside a thermos flask. A drink is poured inside a glass container. The glass inside is covered with silver to stop warmth or coldness escaping. Another silver glass layer stops any coldness or warmth entering the thermos flask.

 

 

Do you wear glasses, or have you ever used a magnifying glass to see a tiny insect? Special pieces of glass are used to help us see more clearly. They are very clear and are made in a curved shape. They are called lenses. Glass lets us see images of ourselves as well.

 

 

 

 

 

 

 

Some glass can make tiny things look bigger.

Look at a bug under a magnifying glass and it will look much bigger! The glass used in microscopes and magnifying glasses is called optical glass. Rays of light pass through the optical glass of the lens in such a way that it makes the image look bigger. This is called magnifying.

 

 

 

 

Glass in telescopes helps you see far away into space.

Telescopes help us see things that are far away. Special optical glass lenses or mirrors in telescopes gather lots of light. This brings the picture of faraway stars and planets closer to your eyes.

 

 

 

 

What do you see in the mirror?

Take a look at yourself in a mirror. Mirrors are made of very shiny glass and have a layer of silver on one surface. Mirrors send back lots of light to your eyes. This lets you see a reflection of what is facing the mirror.

 

 

Have you ever wondered how your computer works? The answer is with the help of glass! Pieces of glass can be made into tiny threads, thinner than a single piece of hair. These are used to send messages between some computers and telephones.

 

 

 

 

 

 

Thin pieces of glass can send messages.

Glass can be made into an optical fibre. This is a rod made of a very thin glass tube, coated in a layer of plastic. Lots of fibres are bundled together in cables. The fibres send light messages and pictures around corners. Flashes of light pass down the optical fibre. These flashes of light are like a code.

 

 

Continue reading "Special glass"

 

 

Glass is not only useful. Glass can be made into works of art. It can be turned into beautiful shapes, patterns and colours. Words can be written on glass using tiny drills. It takes great skill to make, cut and pattern glass, without breaking it!

 

 

 

 

 

 

 

Crystal glass sparkles in the light.

Have you ever seen a glass that seems to sparkle in the light? This glass is called crystal glass. To make crystal glass, a metal called lead is added to the liquid glass mixture. When the glass sets, craft workers can cut tiny shapes into the crystal glass.

 

 

 

 

 

 

 

You can cut patterns into glass.

An artist uses a small drill to draw patterns on glass. This is called engraving. To write on glass, the artist draws letters with a thin needle. A chemical is used to carve the shape more deeply into the glass. This is called etching.

 

 

 

 

 

 

 

Turn a jam jar into a beautiful vase.

Ask an adult to help you make a vase. Take care – glass breaks easily and is sharp. You need a clean empty jam jar, paints and a paintbrush. Put your jar on an old newspaper. Carefully paint a pattern on the jar. Leave the paint to dry. Varnish over the paint – you have a beautiful vase.

 

 

 

Your glass milk bottle may be made from old glass! Much of the glass we use is made from glass that was used before. Old glass can be melted down and made into new glass. Glass is one of the easiest materials to re-use. This is called recycling.

 

 

 

 

 

Recycle glass to help care for our planet.

We need to recycle glass to save energy. It uses up lots of energy to dig sand, limestone and soda from the ground and take them to factories around the world to make glass. But broken glass, called cullet, melts to form new glass. It uses up less energy and fewer resources than making new glass.

 

 

 

 

Different colours of glass are recycled separately.

If you go with your parents or carers to the recycling bins, make sure you do not mix different coloured glasses in the same bin. Different ingredients are used to make different coloured glass so they must be kept separate.

 

 

 

Continue reading "Recycled glass"

 

Today, some glass is mixed with other materials to make it lighter and stronger. Lighter glass is better for our world as it uses up fewer materials. Also, less energy is used to make modern lightweight glass. New types of glass are still being invented.

 

 

 

 

 

 

Glass can help mend human bones.          

Bioglass is a new material made partly from glass. It contains a substance, called calcium that is found in bones. Bioglass can be put inside a person’s body. It melts or dissolves and joins onto bones in the body. Bioglass can help mend and strengthen bones.

 

 

 

Not all glass feels hard.

Foam glass is made by trapping gas bubbles in powdered glass. This makes a spongy material that can protect objects against the cold. Water glass is a powder. It dissolves in water to make a varnish. Water glass doesn’t burn. It can make paper fireproof!

 

 

 

 

 

Glass can be made in space.

Scientists have discovered that making glass in space creates a very pure glass. Some scientists think they could heat up ‘moon dust’ and materials from other planets to make a type of space glass. This could be very useful if humans build on a distant planet in the future.