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  • [DIGITAL TONE]

  • What involves volcanic ash, dangerous chemicals,

  • extreme heat, expert timing, ground pigment,

  • and expert creativity?

  • You guessed it, Fresco painting.

  • Check this out.

  • [MUSIC PLAYING]

  • 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?

  • [MUSIC PLAYING]

  • 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.

[DIGITAL TONE]

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B2 中高級 美國腔

米开朗基罗与壁画科学(Michelangelo & The Science of Fresco Painting | Chemistry Meets Art)

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