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This given diversity of classifications according to the
aspect to consider by each author as well as the different denominations or
concepts from a same type of clay have made difficult from my east inexperience
work, being reduced therefore the synthesis capacity. Finally, I have decided to
expose diverse classifications, since I believe that all of them are valid,
centering specially in the book "Clay to me and glass finish for the ceramist"
and "alive Ceramics", since I considered clearest and they were organized in the
treatment of this thematic one within the consulted bibliography.
THE CLAY. DEFINITION AND PROPERTIES. DEFINITION. We could define the
ceramics like the product set based on the clay or kaolin transformed by the
action of the fire. Another definition could be the mass or body formed by one
or more clays and than have the requirements necessary to be worked at hand, al
winch, with molds, by means of printing or to pressure. In the preparation of a
ceramic paste three main ingredients exist: the plastic elements, thin or
desengrasants and the flux ones. The proportion and quality of these three
ingredients will determine the ceramic product. Plastic elements: They are the
clays and kaolins that form the base of pastes ceramics due to their plasticity.
Thin or desengrasants elements: They are worn out the terra-cotta silica, sand,
pieces (chamota) and the siliceous clays. They are for reducing his excessive
plasticity, to increase the porosity as well as to facilitate the drying of the
object. Flux elements: they are the feldspars, the micas, the lime, the
phosphates, the ground fried ones, the pulverized glasses and the flux, ferrous
and calcáreas clays. We could define the clay like a terrors mineral substance
composed to a large extent of hidrosilicate of aluminum that becomes plastic
when resemblance to the rock becomes damp and lasts and when it cooks. Another
definition could be the disintegration and decomposition of feldespáticas rocks
during million years to give rise to the smallest particles.
PROPERTIES OF THE CLAY. PLASTICITY: By means of the addition of a certain
amount of water, the clay can acquire the form that one wishes. This can be due
to the figure of the grain (at the most small and flattened), the chemical
attraction between particles, the carbonaceous matter as well as an suitable
amount of organic matter. Decrease: Due to the evaporation of the water
contained in the paste a shrinking takes place or decreases during the drying.
Refractory: All the clays are refractory, is to say resist the increases of
temperature without undergoing variations, although each type of clay has a
temperature of baking. Porosity: The degree of varies porosity according to the
type of clay. This depends on the more or less compact consistency that adopts
the ceramic body after the baking. The clays that cook to low temperature have a
higher index of absorption since they are more porous. Color: The clays
present/display diverse colorations after the baking due to the presence in them
of iron oxide, calcico carbonate... |
