WEBVTT - How Does Terracotta Work?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff Lauren Vogelbaum. Here,

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<v Speaker 1>when it comes to durable materials, artists, architects, and homebodies

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<v Speaker 1>alike may need to look no further than terra cotta.

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<v Speaker 1>If you need proof, a look at the army of

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<v Speaker 1>terracotta soldiers that was crafted more than two thousand years

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<v Speaker 1>ago in what's now northwest China. Or consider the Venus

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<v Speaker 1>of Dolni Vestanitze, the oldest known terracotta sculpture, which dates

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<v Speaker 1>from between twenty six to twenty eight thousand years ago.

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<v Speaker 1>There are plenty of other ancient examples of terra cotta

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<v Speaker 1>because humans have long understood the benefits of baked clay,

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<v Speaker 1>which is the basic definition of terra cotta. Today, this

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<v Speaker 1>material can be found everywhere from roofs to gardens. However,

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<v Speaker 1>even though it's widely used, it's not always clearly understood.

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<v Speaker 1>The term terra cotta comes from the Latin for baked earth,

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<v Speaker 1>and it itself has been around since the seventeen hundreds, though,

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<v Speaker 1>of course, as the prior examples show, the practice of

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<v Speaker 1>firing clay has been around for much longer. For the article,

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<v Speaker 1>this episode is based on it has to work. Spoke

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<v Speaker 1>via email with Sarah Barak, the head of Conservation and

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<v Speaker 1>Senior Objects Conservator at Cooper Hewitt the Smithsonian Design Museum.

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<v Speaker 1>She explained terra cotta refers to a low fired porous

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<v Speaker 1>ceramic that has been used for millennia. It generally has

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<v Speaker 1>a reddish or pink color due to the iron in

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<v Speaker 1>the clay, which oxidizes during the firing process. In simple terms,

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<v Speaker 1>clay is the substance that comes from the earth. It

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<v Speaker 1>can be mixed with other materials to make it better

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<v Speaker 1>to work with, and these composites are called clay bodies.

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<v Speaker 1>There are three main types of clay bodies earthenware, stoneware,

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<v Speaker 1>and porcelain. Earthenware is a low fire product, which means

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<v Speaker 1>it's fired at relatively low temperatures one thousand, eight hundred

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<v Speaker 1>two two thousand, one hundred degrees fahrenheit that's about nine

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<v Speaker 1>fifty two one one hundred and fifty degrees elsius. Earthenware

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<v Speaker 1>can be red or white, and when it's red we

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<v Speaker 1>call it terra cotta. Stoneware and porcelain are fired hotter

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<v Speaker 1>so that the clay body undergoes vitrification. That's the process

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<v Speaker 1>in which fired clay becomes glassy, hard and non porous,

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<v Speaker 1>so terra cotta, when unglazed, remains porous, unlike say, porcelain.

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<v Speaker 1>Historic examples of terracotta are common around the world and

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<v Speaker 1>have been found from the Mediterranean to sub Saharan Africa,

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<v Speaker 1>to the pre Columbian Americas to what's now Pakistan and beyond.

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<v Speaker 1>Modern examples abound too, though some of those are based

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<v Speaker 1>on designs that have lasted thousands of years. For example,

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<v Speaker 1>ovens called tandors are still commonly made from terra cotta

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<v Speaker 1>and used to bake flatbreads and other foods throughout South

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<v Speaker 1>and Western Asia, and a familiar site from southern Europe

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<v Speaker 1>to southern Florida are terracotta roofs, also called clay tile roofs.

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<v Speaker 1>With their overlapping plates of brownish red orange clay, these

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<v Speaker 1>roofs can last for one hundred years barring natural disasters,

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<v Speaker 1>and from an energy standpoint, they're good at keeping the

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<v Speaker 1>outside temperature where it belongs. Instead of absorbing the heat

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<v Speaker 1>into your home, the clay tile roofs reflect heat back

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<v Speaker 1>into the atmosphere. The color glazes expand the esthetic possibilities

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<v Speaker 1>and provide water resistance. Terra Cotta makes an ideal solution

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<v Speaker 1>for other areas of buildings too, like walls and floors.

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<v Speaker 1>Iconic structures like New York's Flat Iron Building and Chicago's

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<v Speaker 1>Wrigley Building feature it. But as with those early decorative examples,

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<v Speaker 1>the fired clay is still used to make art and

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<v Speaker 1>esthetic functional pieces. Barack said. Given the low firing nature,

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<v Speaker 1>the ceramic is not as brittle as higher fired wares

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<v Speaker 1>such as porcelain. It can be cast in a mold,

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<v Speaker 1>hand built, or thrown on a wheeld. As with other clays.

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<v Speaker 1>Expressive results can be achieved when artists work this clay

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<v Speaker 1>with tools in a sculptural manner. That means that you

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<v Speaker 1>can find fine art ceramics and vessels in terra cotta.

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<v Speaker 1>With the right types of outer glaze applied, these vessels

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<v Speaker 1>can be water tight, meaning they won't soak up your

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<v Speaker 1>coffee the way that a planter would soak up water,

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<v Speaker 1>and for many people today, terracotta does call to mind

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<v Speaker 1>the classic terra cotta plant pots. These can bring a

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<v Speaker 1>gardener benefits that other materials don't. The thick walls of

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<v Speaker 1>a terra cotta clay pot provide insulation from temperature changes,

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<v Speaker 1>and because they're porous and thus breathe, terracotta pots allow

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<v Speaker 1>for excess moisture to evaporate. That means that you prevent

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<v Speaker 1>trapped water in the pot and thus reduce the risk

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<v Speaker 1>of root diseases and avoid overwatering. However, that also means

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<v Speaker 1>that not every plant is a fit for terra cotta.

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<v Speaker 1>For those that crave consistently moist soil, terra cotta may

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<v Speaker 1>pull away moisture too quickly. Unglazed terra cotta can also

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<v Speaker 1>start to fall apart after many years of soaking up moisture,

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<v Speaker 1>or can break if freezing temperatures catch water droplets inside

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<v Speaker 1>the clay. If you do choose a terracotta pot for

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<v Speaker 1>a plant, here's a tip. Soak it overnight before you

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<v Speaker 1>put soil and a plant in. This will hydrate the

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<v Speaker 1>clay and protect the soil from drying out too quickly

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<v Speaker 1>during the delicate process of transferring a plant to a

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<v Speaker 1>new home. The idea is that if the pot is

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<v Speaker 1>already moist it won't pull as much water from the soil.

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<v Speaker 1>Today's episode is based on the article from Plant Pots

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<v Speaker 1>to Ancient Armies. Terracotta is universal on how Stuffworks dot Com,

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<v Speaker 1>written by Kerry Whitney. Brainstuff is production of iHeartRadio in

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<v Speaker 1>partnership with how Stuffworks dot Com and is produced by

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<v Speaker 1>Tyler Klain. Four more podcasts from my heart Radio, visit

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