What involves volcanic ash, dangerous chemicals,

extreme heat, expert timing, ground pigment,

and expert creativity?

You guessed it, Fresco painting.

Check this out.

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NARRATOR: Support provided by the Glick

Fund, a CICF fund focused on inspiring philanthropy.

Additional support provided by the Christel DeHaan Family

Foundation in honor of the children and families

of Christel House.

Fresco painting using wet plaster

dates back to 1500 BC and the Island of Crete in Greece.

Of course, fresco can be seen around Ancient Greece

as well, often within tombs, depicting

scenes of everyday life.

There are even scenes of a couple dudes just reclining

at a banquet.

However, where we really see some incredible examples

is in the ancient city of Pompeii.

In 79 AD, Pompeii was struck by the eruption

of Mount Vesuvius, which completely buried

the city in volcanic ash.

To our advantage-- definitely not to the people of Pompeii--

much of the city was preserved.

Check out these amazing fresco paintings.

Fresco painting was definitely the wallpaper

of the day, so to speak.

They included scenes from everyday life, which

told stories of daily life, including everything

from being a vendor to a competition between Pompeii

and a rival town, sort of a "West Side Story,"

Sharks versus Jets thing.

Apparently, things got pretty bloody,

which tends to happen when knives and swords get involved.

Fast forward to the 2nd and 3rd century

AD in Rome, where fresco painting makes its way

into the wells and vaults of the underground catacombs,

with biblical scenes on the limestone walls.

Fast forward even further to the 13th century, where

we see fresco work exploding.

Of course, once painters like Raphael and Michelangelo

got a hold of the style, it was the go-to technique.

Now that you know the basic history,

let's explore what is happening within the chemistry,

during the process of fresco painting.

Let's break down what we are going

to need to make this wet plaster mixture.

First is limestone.

Limestone is a very common rock found

in shallow, calm, warm, marine waters.

It has a simple composition consisting

of one calcium atom and one carbon atom and three oxygen

atoms.

To prepare the limestone for plaster,

we must calcify the limestone first,

which means heating it to 1500 degrees

Fahrenheit or roughly three times the temperature

your oven at home can reach.

This process of adding heat breaks down

the calcium carbonate into calcium oxide

and carbon dioxide.

Releasing all the CO2 in the air isn't exactly environmentally

friendly.

The calcium oxide we create from the limestone

is called quicklime.

This quicklime, which consists of only one calcium

atom and one oxygen atom, is now a rather toxic powder

of refined limestone.

In fact, this lime is now an alkali.

An alkali is a basic ionic salt or earth

metal that dissolves in water.

Since this quicklime does have a pH greater than 7,

it can cause a chemical burn on exposed skin.

Keep this in mind as you imagine Michelangelo and his team

working daily with this chemical,

60 feet off the ground.

Dangerous?

You better believe it.

Second ingredient is water or H2O.

What happens next is fascinating.

When we take lime and add H2O, the two

react chemically, creating tremendous amounts of heat.

In fact, tremendous amounts, as in enough to boil water.

Once you add the calcium oxide or quicklime to water,

it is now calcium hydroxide or slate lime.

The third ingredient is sand.

Any idea why they would add sand?

You would think it would absorb the water, right?

Not exactly.

Sand, which is basically microscopic particles

of shells, fish bones, and rocks won't absorb water.

But the space created between these particles

can most definitely hold water and air.

Adding sand created space within the plaster mixture,

allowing the necessary carbon dioxide

to creep in and quicken the creation of calcium carbonate.

But you have to be really careful how much sand and water

you add to the plaster mix.

At the beginning, Team Michelangelo

was adding too much water, which wasn't allowing the plaster

to dry quickly enough.

This caused mold to form very quickly.

Mold on a painting?

Yeah, that's not so good.

Michelangelo, on the other hand, had an ingenious idea.

In order to speed up the drying time of the plaster

and to attain the smoothest surface to paint on,

Michelangelo added ground volcanic ash instead of sand.

This idea had been used within those ancient Roman

catacombs we just talked about.

And guess where he got this ash from?

Remember Pompeii?

Yep, this volcanic ash came from Mt.

Vesuvius, the same volcanic ash that destroyed the city.

As the slaked lime within the plaster mixture

continues to heat up, it reacts to the carbon dioxide

in the air.

Here's what amazes me.

As this carbon dioxide is reintroduced

into the slake lime, the lime begins to harden

and creates these crystals.

These crystals are calcium carbonate, or CaCO3.

Does that look familiar?

It should.

It's limestone.

Yep, you guessed it.

We have come full-circle back to the original molecular

structure we started with.

We're back to limestone.

Before adding paint, you would typically

need to add two layers of plaster, called the arriccio.

After the arriccio layer dries, the final intonaco layer,

or smooth layer, is added.

Of course, Michelangelo and the other fresco painters

had to paint quickly on this wet plaster layer

before it turned back into limestone.

As the paint sinks into the quickly drying intonaco layer,

the pigment is now being blended into the calcium

carbonate or limestone.

Now that the pigment is fused into the limestone layer,

it is very stable and can survive for centuries.

I don't know about you, but I had no idea

just how much science was involved in fresco painting.

Pretty amazing, right?

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On May 10, 1508, work begins.

And man, what a job Michelangelo has in store.

Let me just short-list some of the crazy issues

he will have to face.

MAN: Man, that's really high.

One, he has to remove all the old plaster

within the chapel, which was going to be a huge mess.

Two, the chapel was not going to close while Michelangelo

was painting.

So normal scaffolding covering the chapel floor

wasn't going to work.

Three, it's Rome.

And it can easily get to 90 degrees in the summer,

and that's just standing outside on the ground.

Four, Michelangelo was painting in fresco style, which

had very little experience with and is

one of the most difficult forms of painting ever.

Five, the height within the chapel was crazy.

The ceiling was over 60 feet above the ground.

That's over six stories tall.