How Does Terracotta Work?

From humble planters to ancient statuary, terracotta is a seriously useful material. Learn more about this earthenware in today's epidose of BrainStuff, based on this article: https://home.howstuffworks.com/gardening/garden-design/terracotta.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff Lauren Vogelbaum. Here,
when it comes to durable materials, artists, architects, and homebodies
alike may need to look no further than terra cotta.
If you need proof, a look at the army of
terracotta soldiers that was crafted more than two thousand years

(00:22):
ago in what's now northwest China. Or consider the Venus
of Dolni Vestanitze, the oldest known terracotta sculpture, which dates
from between twenty six to twenty eight thousand years ago.
There are plenty of other ancient examples of terra cotta
because humans have long understood the benefits of baked clay,
which is the basic definition of terra cotta. Today, this

(00:44):
material can be found everywhere from roofs to gardens. However,
even though it's widely used, it's not always clearly understood.
The term terra cotta comes from the Latin for baked earth,
and it itself has been around since the seventeen hundreds, though,
of course, as the prior examples show, the practice of
firing clay has been around for much longer. For the article,

(01:08):
this episode is based on it has to work. Spoke
via email with Sarah Barak, the head of Conservation and
Senior Objects Conservator at Cooper Hewitt the Smithsonian Design Museum.
She explained terra cotta refers to a low fired porous
ceramic that has been used for millennia. It generally has
a reddish or pink color due to the iron in
the clay, which oxidizes during the firing process. In simple terms,

(01:34):
clay is the substance that comes from the earth. It
can be mixed with other materials to make it better
to work with, and these composites are called clay bodies.
There are three main types of clay bodies earthenware, stoneware,
and porcelain. Earthenware is a low fire product, which means
it's fired at relatively low temperatures one thousand, eight hundred
two two thousand, one hundred degrees fahrenheit that's about nine

(01:56):
fifty two one one hundred and fifty degrees elsius. Earthenware
can be red or white, and when it's red we
call it terra cotta. Stoneware and porcelain are fired hotter
so that the clay body undergoes vitrification. That's the process
in which fired clay becomes glassy, hard and non porous,

(02:17):
so terra cotta, when unglazed, remains porous, unlike say, porcelain.
Historic examples of terracotta are common around the world and
have been found from the Mediterranean to sub Saharan Africa,
to the pre Columbian Americas to what's now Pakistan and beyond.
Modern examples abound too, though some of those are based

(02:38):
on designs that have lasted thousands of years. For example,
ovens called tandors are still commonly made from terra cotta
and used to bake flatbreads and other foods throughout South
and Western Asia, and a familiar site from southern Europe
to southern Florida are terracotta roofs, also called clay tile roofs.
With their overlapping plates of brownish red orange clay, these

(03:02):
roofs can last for one hundred years barring natural disasters,
and from an energy standpoint, they're good at keeping the
outside temperature where it belongs. Instead of absorbing the heat
into your home, the clay tile roofs reflect heat back
into the atmosphere. The color glazes expand the esthetic possibilities
and provide water resistance. Terra Cotta makes an ideal solution

(03:24):
for other areas of buildings too, like walls and floors.
Iconic structures like New York's Flat Iron Building and Chicago's
Wrigley Building feature it. But as with those early decorative examples,
the fired clay is still used to make art and
esthetic functional pieces. Barack said. Given the low firing nature,

(03:45):
the ceramic is not as brittle as higher fired wares
such as porcelain. It can be cast in a mold,
hand built, or thrown on a wheeld. As with other clays.
Expressive results can be achieved when artists work this clay
with tools in a sculptural manner. That means that you
can find fine art ceramics and vessels in terra cotta.
With the right types of outer glaze applied, these vessels

(04:07):
can be water tight, meaning they won't soak up your
coffee the way that a planter would soak up water,
and for many people today, terracotta does call to mind
the classic terra cotta plant pots. These can bring a
gardener benefits that other materials don't. The thick walls of
a terra cotta clay pot provide insulation from temperature changes,

(04:27):
and because they're porous and thus breathe, terracotta pots allow
for excess moisture to evaporate. That means that you prevent
trapped water in the pot and thus reduce the risk
of root diseases and avoid overwatering. However, that also means
that not every plant is a fit for terra cotta.
For those that crave consistently moist soil, terra cotta may

(04:49):
pull away moisture too quickly. Unglazed terra cotta can also
start to fall apart after many years of soaking up moisture,
or can break if freezing temperatures catch water droplets inside
the clay. If you do choose a terracotta pot for
a plant, here's a tip. Soak it overnight before you
put soil and a plant in. This will hydrate the

(05:10):
clay and protect the soil from drying out too quickly
during the delicate process of transferring a plant to a
new home. The idea is that if the pot is
already moist it won't pull as much water from the soil.
Today's episode is based on the article from Plant Pots
to Ancient Armies. Terracotta is universal on how Stuffworks dot Com,

(05:32):
written by Kerry Whitney. Brainstuff is production of iHeartRadio in
partnership with how Stuffworks dot Com and is produced by
Tyler Klain. Four more podcasts from my heart Radio, visit
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