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The History and Technique
of Ceramics
The
"CERAMIC"
word drift of the Greek term KERAMIKE, KERAMOS derivation, that
means clay. Ceramics are the set of activities destined to the
elaboration of all the species of objects, with adobe
of any class, decorated or not, using it property that possess the molding
clay easily in the
raw adobe state (wet), acquiring hardness to the measure that
advances its drying or for cooking effect.
It was during the Neolithic period,
phase of the development technician of the societies human beings,
correspondent to its access to a productive economy, that the
ceramics were invented. This period, characterized for the
development of new techniques has however as factor of primordial
importance the establishment of new relations between the man and
the natural way, decurrently of the discovery of ways to control and
to develop the resources for its sedentary
life.
It was considered during much time
that the ceramic was one characteristic of this period. However the
recognition of a pre-ceramic Neolithic period in the Next East
(Jericó) and the ceramic vases discoveries in nomads groups dated
of about 6000 AC. in Japan, compels us to consider it the existence
of two phases: the pre-ceramics between the end of VIII millennium
AC. and the principle of the VI and ceramics to follow to this date
and was drawn out until the age of Bronze.
It was in the Southwest of Asia
(Iran, Palestine and South of Turkey) that spontaneity gave the
wheat and the barley, as well as existed in the wild state bovine
and goat cattle that had
allowed the revolution (passage
to a production economy) above referenced.
It
is not therefore to find odd that the initial development of
ceramics if has given in the Next East, seen to have there been that
the necessity was verified to store collected foods of agriculture;
of houses to shelter an increasing population; of symbols that
satisfied the spirituals necessities
and ovens that transformed the decorative wheat's
flour into bread
that led to the construction of vases, bricks, statuettes and
elements in clay.
How to
Portugal has that to relate some following aspects: it had a first
period where if they had revealed the European and Mediterranean
influences for
the appearance and development of this art, through the
"invaders" in the first case and of the merchants in second.
The appearance of a specific type of ceramics proceeding from a
situated culture in the Tejo's Valley
and that later was spread for all
the Europe: the campaniform ceramics.
The
existence of typical ceramics (ceramic Iberian), to the time of the Romans
arrival and the
importance of these and later of the Arabs for the future
development of the pottery.
The
existence of various
regional types during the Average Age, some of which last until to
the present.
The
great development verified in last centuries XVII and XVIII,
especially in this last one, due to existence of countenance
ceramists as Brioso and Vandelli and to the foundation of Plant of
the Rato,
that was in the base of the appearance of other important plants for
all the territory. The appearance in century XIX of the porcelain (Vista
Alegre) and of the
fine faïence (Sacavém) in part as reaction
to the invasion of our market for English products, better and
cheaper, because manufactured for the new processes left the
Industrial Revolution.
The
increase of the number of plants verified in the ends of century XIX
and first decades of century XX and its decrease in the following
decades, as consequence of the industrial
concentration that was mark of the "great rising
industry", process that the ceramics were not indifferent.
Ceramic
it is the common denomination to all the articles or objects
produced with clay and burnt/baked to the fire. The transformation
of the adobe in ceramics happens during the burning. When the clay
is burnt and if it becomes firm, in its first burning get the call
biscuit, that although more not to come back to the plastic state
still it possess fragile
characteristic, therefore to fall themselves in the soil or to take
a stronger collision, has been broken in many pieces.
The
clay exists in all terrestrial surface. Some types are found at
open sky and others in underground mines or deposits. The clay when
removed of the nature generally it contains undesirable
bodies, organic
impurities, and therefore needs to be benefited through mechanical
and chemical processes. For each category of the ceramic production
the production of the argillaceous masses needs the addition or the
withdrawal of elements in its composition, in accordance with its
application, thus preventing the occurrence of cracks.
Of the many existing types of clay the masses ceramic are produced
that are used in the
manufacture of ceramic utensils as roofing tiles, bricks, floors,
etc.; that it is the structural ceramic call.
The
masses of adobe are raw employees in the construction of housings.
It has the called white ware in sanitary parts, tiles, electric,
conducting floors of high impact, refractory, electric insulators,
etc. And the ceramic masses for the artistic ceramic called.
The Ceramics can be defined as material inorganic,
nonmetallic gotten generally after thermal treatment in high
temperatures. The ceramic materials are manufactured from natural
and synthetic raw materials classified in. The natural ones more
used industrially are:
clay, caulino, quartz, feldspate, filite, talc, calcite, dolomite, magnetite,
chromites, bauxite, graphite and zirconium
The
synthetic ones, among others include alumina (aluminum oxide) under
different forms (calcimined, electro funded); silicon carbonate and
the most diverse inorganic chemical products.
Ceramics have electric properties as isolating of high-voltage, in resistances,
as the memory in computers, candles in the internal combustion of
engines and, more recently, in applications of superconductors high
temperature.
Ceramics are essential for the
construction industry, for the petrochemical industry, to generate
electricity, for the communications, space exploration, medicine,
sanitary. Porous porcelain done ceramics filters that can isolate
microbes and bacteria of milk and drinking waters, separate dust of
gases and remove particles solid of liquids.
Ceramics shields, which is light and resistant to the impact, have
been confectioned to protect military airplanes, vehicles and
soldiers. Ceramic mono-crystals have important mechanical
applications, electric and optic. So delicate ceramics include items
that they can be broken by a light touch, so resistant that they can
protect our proper body and so lasting that they remain after
thousand of more remote years disclosing to us it history of our
ancestral ones.
One of the operations most
important of the confection of objects in ceramics is the glass. The
objective of the glass is to become impermeable objects of adobe to
the water, and moreover it is also of giving color to them. They can
be gotten glass of some qualities- of color, colorless, transparent
or cloudy.
For the application of the glass, it is started for glassing
the part.
After the glass being dry, it is painted the piece, using or
not glass inks for ceramics of colors.
The glassed objects
have of being placed in the oven in top of small adobe tripods, with
the greater well-taken care, and in way not to be leaned ones to the
others. The objects go then to the cooking, to glass: in this cook
the oven heats until the final a temperature of 1.000 the 1,0400, in
accordance with the instructions that follow the dust of glass. Of
this time the temperature regulator of the oven can be put in the
maximum. If to appear in the glass small cracks, is because glass
are not of appropriate quality for the type of used adobe (the
contraction coefficient was different). These containers are badly
waterproofed.
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