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.

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?

Before I say anything more,

now would be a good time to pause the video and discuss.

Okay, you ready?

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.

Now, for the next episode,

there's a lunar eclipse that's going to happen.

I reached into my question jar

and chose three questions about lunar eclipses

that I'm thinking about answering.

When this video's done playing, you'll get to vote on one.

You can choose from what's the difference

between a solar and lunar eclipse,

why does the moon turn blood red during a lunar eclipse

or where does the word eclipse come from?

So submit your vote when the video's over.

I wanna hear from all of you watching.

There are mysteries all around us.

Stay curious and see ya next week.