How is glass made?

Hi, it's Doug.

I recently came across this unbelievable video.

It was taken at a hotel in Texas

where on the roof of the hotel they have this pool that hangs off the edge

and it has a glass bottom.

Look at this.

Would you go in there?

Would you trust this glass?

Someone named Benjamin has a question about glass.

Let's give him a call now.

Hi, Doug.

Hi, Benjamin.

I have a question for you.

How's glass made?

That's a great question.

It's funny, right?

Think about just how many objects around you are made of glass.

Without glass, we'd have no windows,

no windshields for our cars,

no drinking glasses or eyeglasses,

no skyscrapers or smartphones

and yet it's really not obvious at all where glass comes from.

Like, if you're sitting there and you have a table or a desk in front of you like this,

that's wood.

I'm guessing you know that wood comes from a tree

or this statue here is carved from stone.

You know where that comes from.

But glass?

Glass is a material that has to be made.

How do they make it?

Where does it come from?

Well, believe it or not,

glass is made by taking a bunch of sand and getting it so hot that it melts.

It's one of the most amazing things to watch how it's made

because in order to melt sand, you have to use a special type of oven that can get super hot.

It's called a furnace or a kiln.

Here, you can see someone loading some sand into the furnace.

Once it gets hot enough, it will melt or become liquid

and when you get something this hot, you can see it glows just like lava.

This isn't lava though. It's molten sand.

And as it cools, it will start to look more familiar to you.

It becomes solid glass.

To make a flat sheet of glass like you'd use for a window,

they melt sand until it's molten

then they pour it out and roll it into a flat shape like this

and carefully allow it to cool.

More fancy objects like a glass vase are even more fun to watch.

This involves a special skill called glassblowing.

You can see here it starts with this person taking a big glob of molten sand

and getting it on the end of a hollow pipe

then she blows air into the pipe.

You can actually blow a bubble into it

which might end up being the open part of the vase.

The molten glass has a similar thickness as honey.

They carefully shape it the way they want it and keep turning it and turning it.

As it cools, it becomes solid.

Artists can make amazing sculptures with glass.

Believe it or not, this artist is making a glass swan.

So that's how glass is made

but it's kind of weird, isn't it? I mean...

how did people ever discover that if you melt sand it makes glass?

We've been making glass for a long time.

So long ago now that no one knows for sure who was the first person to discover that if you melt sand it makes glass

but some of the earliest objects made of glass come from ancient Egypt,

a place covered in desert sand.

Could it be that someone long ago had a campfire

and noticed that the heat of their fire melted the sand beneath it?

No one knows for sure but it's possible.

That's all for this week's question.

Thanks, Benjamin, for asking it.