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| art making pottery |
When the clay has a specific dryness of around 75 to 85%, it becomes "leather hard", when it can be more easily moulded into shape and to which other pieces can be added. Over the centuries of this trade many tools have been invented to aid in the moulding process, the most important of which is the potter's wheel , where the spinning mass of clay in the centre of the wheel can be formed into a vase or other similar vessel with a consistent circumference. While some prefer the consistency and speed of the potter's wheel, arguing for the spontaneity of shape formed while the wheel spins, others prefer to form shapes in the manner before the wheel was invented: from ground up in a standing and stagnant position, arguing that this method produces more individually unique pottery subject to a more robust imagination.
When using the wheel, it requires a certain amount of skill to first centre the clay, then to open it by creating a hollow dip in the centre, then to create a floor with a rounded bottom inside, then to throw the clay by drawing it upwards to shape walls of even thickness, and finally to trim and turn it by removing excess clay and refining its shape into its final form.
Although the wheel can speed up work and aid in creating more consistently similar shapes, the general shapes themselves are more limited to ones with radial symmetry and a vertical axis. But handles, lids and other extremities can be added at the end, or the produced shape can itself be distorted by bulging and other methods, to create greater uniqueness.
Over time, machines have been invented to replace or aid the potter's hand, speeding up production further, but while simplifying any individuality, or removing unique traits.
Once the final shape is complete, the pottery can be decorated by incising patterns on its surface, embedding on it foreign objects (such as with seashells in my Item 12 or 18 through the link at the bottom), and eventually glazing and colouring it in any number of ways.
Prior to glazing, additives such as sand can be mixed into the clay, creating particular textures once the pottery is heated and glazed. Combustible particles can even be mixed in or pressed onto the surface to produce different effects during heating.
Mixing different clays of different colours can also produce interesting results, referred to as "agateware", after the quartz mineral agate which has bands or layers of different color blended together. In this process, the potter is careful not to overmix the different clays so that the individual colours are distinguishable, and the choice of clays is also important as they must have similar thermal movement characteristics during the heating stage in the kiln.
Prior to heating in the kiln, the pottery can also be finely polished, referred to as burnishing.
The next stage, still before heating, can be engobing, which is to add on a layer over top of the pottery, often by dipping the entire shape into a bath, or by painting it on the pottery's surface - a method used since pre-historic times. This outer clay slip is often high in silica, and can be incised with engravings to pierce through the new surface, revealing colours of the clay beneath. A second clay slip of different colour can be further added, and later incised, to produce patterns of different colour, much like the procedure used when making Easter eggs.
Another method of applying design to the surface is similar to lithography, whereby an image or colour on a decorative design layer is applied to the surface using a backing paper, printed onto the surface much like screen printing. Once the design has been transferred, a protective layer is applied, which may include a low-melting glass.
After this, gold can be applied or painted on in various ways for extra fancy pottery.
And finally, we have the glazing stage, which coats the pottery with a protective, colourful and decorative surface. Its colour and appearance often changes during heating, and the sealed result protects the inner clay from destructive moisture or water. Different minerals and application techniques can be used to produce different effects, giving the pottery its final touch and personality.
Once the clay mould has been prepared, the object is then subjected to firing, which is the process of heating the vessel at different temperatures to harden it, after which it can be called pottery. Different materials require different temperatures, but all firing is generally at or above 1000 degrees centigrade. There can be several stages of firing, which fuse together different minerals, while regulating air intake into the kiln can produce different degrees of oxidation of the clay and outer glaze.
When using the wheel, it requires a certain amount of skill to first centre the clay, then to open it by creating a hollow dip in the centre, then to create a floor with a rounded bottom inside, then to throw the clay by drawing it upwards to shape walls of even thickness, and finally to trim and turn it by removing excess clay and refining its shape into its final form.
Although the wheel can speed up work and aid in creating more consistently similar shapes, the general shapes themselves are more limited to ones with radial symmetry and a vertical axis. But handles, lids and other extremities can be added at the end, or the produced shape can itself be distorted by bulging and other methods, to create greater uniqueness.
Over time, machines have been invented to replace or aid the potter's hand, speeding up production further, but while simplifying any individuality, or removing unique traits.
Once the final shape is complete, the pottery can be decorated by incising patterns on its surface, embedding on it foreign objects (such as with seashells in my Item 12 or 18 through the link at the bottom), and eventually glazing and colouring it in any number of ways.
Prior to glazing, additives such as sand can be mixed into the clay, creating particular textures once the pottery is heated and glazed. Combustible particles can even be mixed in or pressed onto the surface to produce different effects during heating.
Mixing different clays of different colours can also produce interesting results, referred to as "agateware", after the quartz mineral agate which has bands or layers of different color blended together. In this process, the potter is careful not to overmix the different clays so that the individual colours are distinguishable, and the choice of clays is also important as they must have similar thermal movement characteristics during the heating stage in the kiln.
Prior to heating in the kiln, the pottery can also be finely polished, referred to as burnishing.
The next stage, still before heating, can be engobing, which is to add on a layer over top of the pottery, often by dipping the entire shape into a bath, or by painting it on the pottery's surface - a method used since pre-historic times. This outer clay slip is often high in silica, and can be incised with engravings to pierce through the new surface, revealing colours of the clay beneath. A second clay slip of different colour can be further added, and later incised, to produce patterns of different colour, much like the procedure used when making Easter eggs.
Another method of applying design to the surface is similar to lithography, whereby an image or colour on a decorative design layer is applied to the surface using a backing paper, printed onto the surface much like screen printing. Once the design has been transferred, a protective layer is applied, which may include a low-melting glass.
After this, gold can be applied or painted on in various ways for extra fancy pottery.
And finally, we have the glazing stage, which coats the pottery with a protective, colourful and decorative surface. Its colour and appearance often changes during heating, and the sealed result protects the inner clay from destructive moisture or water. Different minerals and application techniques can be used to produce different effects, giving the pottery its final touch and personality.
Once the clay mould has been prepared, the object is then subjected to firing, which is the process of heating the vessel at different temperatures to harden it, after which it can be called pottery. Different materials require different temperatures, but all firing is generally at or above 1000 degrees centigrade. There can be several stages of firing, which fuse together different minerals, while regulating air intake into the kiln can produce different degrees of oxidation of the clay and outer glaze.
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