Read below and create two discussion each one with 20- 25 words
Refined (Porcelain)
IN JANUARY 1962 the Miodownik family was gearing up to celebrate the marriage of my father, Peter Miodownik, to his fiancée, Kathleen. Wedding plans were in place, friends had been invited, religious instruction for the ceremony between this Jewish man and Catholic woman was ongoing, nerves were jangling, free love may or may not have been practiced, but wedding presents for the young couple were definitely being ordered, one of which was a bone china tea set.
It was delivered to my parents’ house in a wooden crate from the Harrods department store. Once the cups and saucers had been removed from their bed of sawdust, they were washed and placed on the kitchen draining board. Here they got the first view of their home: a bare but large kitchen in the suburbs of London. One of the tea cups slid from the sink top on to the floor, but it bounced off the linoleum rather than smashing, much to the joy of the happy couple, who grinned at each other in amazement. A good omen, they decided, and so it turned out: the cups served them their whole marriage.
In the early days, the porcelain tea cups had to share a kitchen cupboard with some wooden cups that my mum had brought with her from Ireland.
This must have filled them with horror. Wood has a rustic appeal, of course; it is a beautiful and natural material, and its organic simplicity is appealing to those who long for a more rural life. But as a material to drink out of it is hard to defend. It has a strong taste and absorbs other flavors into its pores with ease, distorting the taste of the next drink. Metal cups were also knocking around the kitchen at that time. Apparently they were from a camping set, and had been brought into the kitchen because the newlyweds had few others. But metal is not much better for drinking tea out of than wood. We put metal cutlery in our mouths all the time, preferring it to other materials because its stiffness
and strength allow forks and spoons to be thin and sleek without bending or snapping. Crucially, their shininess and smoothness make it easy to detect whether they have been completely cleaned since they were last in another’s mouth. But the material conducts heat too well to be used for hot drinks. It also sounds brash and loud, an acoustic signature that doesn’t match the sophisticated flavors of tea.
Like most objects designed for children, they are colorful and robust, and this suits the drinks they contain, which tend to be much sweeter and fruitier than tea. The feeling of soft plastic in the mouth, meanwhile, is warm, comforting, and safe. They look jolly and sweet, the material mirroring the state of infancy. It would be appropriate if plastic juice cups grew up to be ceramic tea cups as they got older, becoming stronger, stiffer, and more distinguished.
But sadly what happens to plastic cups is that they die young, structurally degraded by the UV rays of the sun. Every picnic takes years off a plastic cup’s life. Eventually they go yellow and brittle, and finally fall apart. Ceramics, on the other hand, are impervious to UV degradation or chemical attack. They resist scratching better than any other material, too. Oils, fats, and most stains just bounce off them. Tannins and a few other molecules do stick to them, but acid or bleach cleans them fairly easily. As a result, ceramics keep their looks for a very long time. In fact, if it wasn’t for the crack in my cup, which runs from its lip to its handle and has become stained with tannins, it would look pretty much the same as it did fifty years ago.
There are very few things you can say that for. Paper cups may seem sustainable because paper is recyclable, but the wax coating required to make them waterproof makes this almost impossible. For real sustainability, we must look to ceramics. Practicalities aside, there is a social stigma attached to serving tea in paper, plastic, metal, or pretty much any material other than ceramic. Tea drinking is about so much more than ingesting fluid: it is a social ritual and a celebration of certain ideals.
Ceramic cups are an essential part of this ritual—an essential part, therefore, of a civilized home. The story of how ceramics got their high status dates from a long time ago, before paper, before plastics, before glass, and before metal. It all began when humans started putting the clay from river beds into fires in the realization that they could transform it. It didn’t just dry out. No, something else took place that turned the soft squidgy clay into a rigid new material that had almost all the qualities of stone.
It was hard and strong and could be shaped into storage and collecting vessels for grain and water. Without these vessels, agriculture and settlements would have been impossible, and civilization as we know it would never have got off the ground. Roughly ten thousand years later, these vessels came to be known as pots and this simple species of ceramic as pottery. But these early ceramics were not really like stone. They were fragile, easily broken, dusty, and porous (because at a microscale their skin was full of holes). Terra cotta and earthenware are modern relatives of these early ceramics. They are beautifully simple to make but are still terribly weak.
Of all places, the oven is where ceramics should be comfortable, because that’s where they were formed, but terra cotta fails time and time again. The reason is that liquid seeps into its pores and then expands into steam when heated, turning the pore into an exploding micro-crack that eventually links up with other micro-cracks like tributaries of a river, and
finally erupts on the surface of the terra cotta dish, spelling an end not just to the dish but, as often as not, to the meal within it, too. Unlike metals, plastics, or glass, ceramics cannot be melted and poured. Or rather, we don’t have the materials that can withstand the temperatures required to contain such liquids. Ceramics are made from the same stuff as mountains, rocks, and stone, whose liquid form is the lava and magma of the Earth. But even if lava could be captured and poured into a mold, it would not form a strong ceramic—certainly not one that you would recognize or make a cup from.
What forms is, of course, volcanic rock, which is full of holes and imperfections.
It takes millions of years of heat and pressure deep inside the Earth to turn such stuff into the so-called igneous rocks and stones that make up mountains. For these reasons, attempts to make artificial substitutes for rock either use chemical reactions, which is how cement and concrete work, or, in the case of pottery, involve heating up clay in a furnace, not to melt it, but instead to take advantage of a very unusual property of crystals. Clay is a mixture of finely powdered minerals and water. Like sand, these mineral powders are the result of the eroding action of the wind and water on rocks, and are in fact tiny crystals.
Clays are formed often in river beds, where these eroded minerals are washed down from mountains, settle on the river bed, and form a squidgy, soft dough. Different mixtures of minerals result in different kinds of clay. In the case of terra cotta, the crystals are usually a mixture of quartz, alumina, and rust, which gives the terra cotta its red color. When this is heated up, the first thing that happens is that the water evaporates, leaving the tiny crystals aggregated in a kind of sand castle with lots of holes where the water used to be. But at high temperatures something special happens: atoms from one crystal will jump on to another nearby crystal and then back again.
The atoms in some crystals, however, do not return to their original position, and gradually bridges of atoms are built between the crystals. Eventually, billions of such bridges are built, and the collection of crystals has become something more like a single continuous mass. The reason the atoms do this is the same reason why any two chemicals react: within each crystal, all of the atom’s electrons are part of a stable chemical bond with its neighbors—they are, as it were, “occupied”—but at the edges and surfaces of the crystal, there are “unoccupied” electrons, ones that have no other atoms to bind to, the equivalent of loose ends.
For this reason, all of the atoms in a crystal seek a position within the body of the crystal rather than at its surface; or, put another way, those atoms at the surface of the crystal are unstable, available, and liable to relocate if an appropriate opportunity to do so comes their way.
How firing of ceramics transforms an assembly of small crystals into a physically coherent single material. Usually, when the crystals are cold, these atoms don’t have enough energy to move around and do something about their predicament. But when the temperature is high enough, the atoms can move around: they set about reorganizing themselves so that as few of them as possible are forced to inhabit a position at the surface of the crystal—so that, in fact, there is less surface overall. In doing so, they reshape the crystals to fit together as fully and economically as possible, eliminating the holes between them. Slowly but surely the collection of tiny crystals become a single material. It’s not magic, but it is magical. That’s the theory, of course, but the chemistry of some clays makes this easier to do than that of others.
The advantage of terra cotta clays is that they are easy to find, and this reshaping process will happen at relatively low temperatures—the temperature of a fire or simple wood furnace will do. This means that making terra cotta requires only a small degree of technical know-how. As a result, whole towns and cities are built from the stuff: the common house brick is essentially a form of terra cotta. The big problem with terra cotta ceramics, though, is that they never get rid of all the holes, and so never become fully dense.
This is fine for house bricks, which only need to be fairly strong, and once cemented in place will not be bashed around or heated and cooled repeatedly. But it is a disaster for a cup or a bowl, which will have a thin body but be expected to withstand the rigors of the kitchen. They just don’t last: one small knock and the cracks start to grow from the pores and never stop. It was the potters of the East who solved the problem of fragility and porosity. Their first step was to realize that if earthenware was covered with a particular kind of ash, this ash would transform during firing into a glass coating that would stick to the outside of the pot.
This glass skin would seal all the pores on the outside of the earthenware. And by varying the composition and distribution of the glaze, the pots could be colored and decorated. This not only stopped water getting in but it suddenly opened up a whole new aesthetic realm for ceramics. These days you quite often see this glazed earthenware. There is certainly a lot of it in my kitchen—in the form of the tiles that cover the walls around the sink and cooking surfaces, making them easy to clean.
