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CURIOUS CAT:Hello, children. What are you up to?

BOY:We're putting a picture onto the glass window.

GIRL:So the light can shine through.

CURIOUS CAT:Good thing you have glass windows in the classroom. Do you want to find out how glass is made?

BOY:Yeah.

GIRL:Yeah.

CURIOUS CAT:Well, glass starts off as sand.

CURIOUS CAT:'A bit like the sand you might find on a beach. But to make clear glass, a special sand called Silica Sand is used. This fine sand is needed because it's very pure, and does not contain any other unwanted chemicals. This special sand comes from all over the world.'

CURIOUS CAT:To find out what happens to the sand, Susan will show you around the glass factory. Off you go.

GIRL:Is glass only made of sand?

SUSAN:No, sand is just the main ingredient that goes into glass, but it also has lots of other things in it, like soda ash and limestone. Do you wanna go and have a look?

CURIOUS CAT:'Glass is made from sand, soda ash, and limestone, which are three minerals that come from the ground. They are mixed together, then put into a very hot oven called a furnace.'

SUSAN:So, this is where all the raw ingredients are fed into the oven and melted, so it has to be very, very hot. So it goes like-- it's almost like toffee. Do you want to have a look? Yeah?

GIRL:Yeah.

SUSAN:Right, here. If you want to step up on here.

BOY:Oh my gosh.

BOY:That is so cool.

GIRL:Wow. It looks like cocoa.

CURIOUS CAT:'The furnace needs to be super hot. In fact, it's 1,600 degrees Celsius. This is what it looks like inside.'

GIRL:Wow.

SUSAN:So now, we've seen the raw ingredients melting in the oven, almost like toffee. So what happens next is that that spreads across a big bath, which is full of liquid metal, and that substance, that gloopy substance, it floats along the top, and spreads out so that it's perfectly flat. So what we're gonna do is go to the lab and we're gonna do a little experiment so you can see what I mean, okay? Let's go. So, let's pretend that this oil is our liquid glass, which is made up of our different raw materials. Remember? We've got our sand–

BOY:Yeah.

SUSAN:And our soda ash here, and limestone.

BOY:Yeah.

SUSAN:So this is our liquid glass. And this water is our liquid metal.

BOY:Yeah.

SUSAN:So, let's see what happens when we pour the glass onto the liquid metal.

MUSIC

SUSAN:So what's happening? Can you see what's happening?

BOY:It's floating on top of the water.

SUSAN:That's right. So, the liquid glass floats on top of the liquid metal and doesn't mix together, so it stays the glass stays perfectly flat.

GIRL:Oh, cool.

BOY:It's wicked.

CURIOUS CAT:'That's brilliant. So just like this oil and water, the glass in the furnace floats on top of the liquid metal, and stays completely flat. Now, let's see how the real glass is doing.'

SUSAN:So, this is the first time that we can actually see the glass coming out. Do you want to have a look? You can stop in here. And you can see it going past.

BOY:Yeah.

GIRL:Look at that. It looks like see-through paper.

SUSAN:So at this stage, it's about half as hot as it was and it's still quite soft.

CURIOUS CAT:'For the glass to get hard, it needs to cool down very slowly.'

GIRL:Why is the glass cooled slowly?

SUSAN:Because if we cool it too quickly, then it could break. And at this stage, we're also checking for any other faults in the glass, like stress breaks or bubbles, which are obviously no good. Okay? Now, from this point, the glass is one continuous ribbon right back to that bath of liquid metal. And so the next stage is to cut it into pieces.

CURIOUS CAT:'This long piece of glass is far too big to be used in our homes. So it needs to be cut down.'

SUSAN:This is what it uses to cut it. You see, it scores across the glass with these little wheels. That cutting bridge that's going across there, it makes a line-- a little line in the glass across. And then, when it gets to these little wheels, it just gives it a little knock and it just breaks perfectly along that line, and then it moves away. Like, watch, watch here.

SUSAN:It's gonna come up and break it. Watch.

BOY:Look at that.

CURIOUS CAT:'Wow. What a clever machine.'

SUSAN:If you look up ahead, you'll see the line go past. There it is. It's hard to see, isn't it? Because it's so clear. See it?

GIRL:Oh, yeah.

BOY:Yeah.

GIRL:Yeah.

SUSAN:And then it's gonna go along, and those wheels are just gonna break it out. Up there. Ready? There it is. And then that piece of glass goes away.

GIRL:Cool.

GIRL:How old do you think this machine is?

SUSAN:This machine, it is 11 years old. Eleven. It's called Claritude. That's its name.

BOY:So it's a boy?

SUSAN:Okay. So here, we're gonna see the glass being stacked onto the pack.

CURIOUS CAT:'Once the glass is cut, it travels along to a machine that uses sockets to gently pick up the glass and stack it, ready to be used in our homes.'

SUSAN:These big machines are used to lift up the packs of glass and move them around, and put them on the lorry, so that it can be delivered to our customers.

SUSAN:So you've seen the raw ingredients go in one end, and glass come out the other end. And that's how glass is made out of sand.

CURIOUS CAT:Hello, children. How was your journey?

GIRL:The glassmaking factory was great.

BOY:'We saw glass being made out of sand. The sand is mixed with other ingredients. And put into a big hot oven, and heated up until it is extremely hot. And then it all melts.'

GIRL:'Then it's poured onto a bath of liquid metal, but they don't mix. The glass floats on top. Then it goes really smooth and flat.'

BOY:'They have to cool it down slowly, or it would break.'

GIRL:'Then the glass is cut into different sizes. And then it is stored until it is needed.'

CURIOUS CAT:Well done. Now you know all about making glass. What an exciting journey you've had. Now it's time to say goodbye.

BOY:Bye-bye.

GIRL:Goodbye.

CURIOUS CAT:Goodbye, children.