Ceramics

Process and Early Civilization

Origins of Ceramics

Clay has been shaped and formed as far back as the Ice Age (37,000-12,000 BC). Representations of animals have been found throughout Europe.

Ceramics

Clay is transformed into ceramics when it is heated to a temperature between 1680 degrees and 2420 degrees Fahrenheit. The pottery becomes hard and retains a permanent shape.

It was not until 6000-4000 BC that knowledge of the firing process became well known. History has left no record as to how the ceramic process was actually discovered. There are three theories as to how the firing process was discovered.

Early Decoration

Around 4000 BC the first glazes were developed in Egypt. Glazes serve both a practical and decorative purpose. The Egyptians first used the glazes to decorate beads and tiles.

Source of Clay

A significant portion of the Earth’s crust is composed of granite

Clay

Clay is produced through the weathering of granite.

Granite is the parent rock of clay. When broken down it produces feldspar.

Feldspar is composed of alumina, silica and alkali.

Clay

Further weathering replaces the alkali with water. Clay, in its purest form is identified,chemically, as:AluminaSilica Water

ORAl2O3 * 2SiO2 * 2H2O

Pure Clay

Pure clay would be white, soft and mushy.

Impurities

Clay usually contains a number of materials which allows it to become more workable, as well as more attractive. These impurities may alter the:

Maturing Temperature

Color

Texture

Plasticity

Porosity

Properties of Value

Clay has three primary characteristics which make it useful for pottery:

Plasticity

Porosity

Vitrifiability

Plasticity

The ability to form or mold a piece of clay, and the fact that the clay will then hold that shape.

Porosity

Clay must contain water in order for it to function in the plastic state.

The water must be able to evaporate out of the ware completely before the piece is placed within the kiln for firing.

The porous nature of clay allows this moisture to evaporate.

Vitrifiability

The melting or fusing of portions of the clay body at specific temperatures.

This allows the fired object to be exposed to moisture, and still retain a hard, firm shape.

Stages of forming, construction and decoration

Plastic

Leather Hard

Bone Dry

Bisque Fire

Glazing

Plastic

During this stage the clay is soft, wet and pliable. It is during this stage that most ceramic pieces are formed. Types of construction during this stage are:PinchDrapeCoilSlabCore MoldsWheel ThrownSlip Casting

Leather Hard

The clay still contains considerable free water, but enough has evaporated so that the clay pieces are firm enough not to bend. The relatively high moisture content allows the joining of these somewhat rigid pieces of clay. Dry clay cannot be joined to another piece of dry clay. Type of construction during this stage:Slab

Bone Dry

All free water has evaporated. The piece is now ready for the first firing. All free water must be eliminated in order to avoid bursting within the kiln.

Green ware

These first three stages result in green ware. This term refers to any ceramic object which is complete in construction but has yet to be fired.

Bisque Fire

The green ware is put into the kiln and heated to approximately 1856 degrees Fahrenheit.

There is partial fusing of clay particles.

After this stage, green ware becomes bisque ware.

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Glaze Fire

At this time the bisque ware is usually (not always) coated with a layer of glaze. This material is a liquid mixture of a variety of glass-forming materials. This process accomplishes two things:

Seals

Decorates

Glaze Fire

The pot, with its coating of glaze is returned to the kiln for another firing. The glaze fire is usually at a higher temperature than the bisque fire. In our case the glaze firing is usually 2350 degrees Fahrenheit. This firing melts the glaze, fuses it to the pot, and fully matures the clay body. Total shrinkage at this point is 10-15%.

Glaze Fire

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Oxidation Glaze Fire

Oxygen rich atmosphere.

Glaze reacts to the oxygen in the air and produces a clear, brilliant color.

Clay maintains a clear color as well.

Reduction Glaze Fire

Oxygen depleted firing atmosphere.Airflow is reduced at certain temperature and the open fire is moderately smothered, causing incomplete combustion.Oxygen is drawn from materials in the glazes and clay body.Allows for multiple glaze effects from different metallic oxides.

Raku

Pieces are fired quickly to a low heat.When the glaze has matured, the piece is pulled from the kiln and placed into a receptacle containing combustible materials.Crazed (cracked) surfaces, metallic flashing and other special effects are unique to this process.

                                                                                                                                                   

Clay Types

Earthenware

Stoneware

Porcelain

Earthenware

Matures at 1856 F

Color is usually red-brown, but can also be white

Light in weight

Fairly porous.

Usually smooth

                                            

                

Stoneware

Matures at 2205 F or higher

Color is usually brown, gray, buff or tan

Usually rough in texture

Quite hard, dense and heavy

Type of clay used at VHS

Porcelain

Matures at 2205 F or higher

Color is usually white

Surface is very smooth and glasslike

Extremely dense

Pyrometric Cones

They are used to accurately measure the temperature within the kiln. These cones are made from clay that is formulated to melt at a specific temperature. Cone numbers are applied to clays and glazes as a universal method of determining firing temperatures and compatibility.

Firing Temperatures

Cone 06 is the usual temperature for our bisque fire, and is the maturing temperature for earthenwares and low fire glazes.

Cone 06 is 1856 F

Cone 10 is the temperature at which our stoneware clay and glazes mature.

Cone 10 is 2350 F

Elements and Principles of Art

The elements of art are the building blocks of art. Think of them as the ingredients that artists use to create an artwork.

The Elements of Art.

ColorValue Line TextureShape Form Space

Color

Color is produced by the way our vision responds to different wavelengths of light. When a ray of white light passes through a glass prism, the ray is bent creating six individual bands of color.

Color

Colors have three properties that can be defined and measured:

Hue

Intensity

And Value

Hue

Hue – refers to the name of a color itself, such as “blue” or “red”. For easy study the colors of the spectrum are arranged in a circle called a color wheel.

Intensity

Intensity – The quality of brightness and purity of color. Adding neutral colors to a pure hue results in a loss of intensity.

How would you describe the use of color in this Picasso painting?

Compare and contrast the way that color is being used on these two pots

Value

Value- The lightness or darkness of colors.A color plus white = TintA color plus black = Shade

Value

This painting by Picasso is made up primarily of shades and tints of the color blue.

How would you describe the use of value in David Roberts naked raku vase?

Line

Line- a path of a moving point through space, refers to the continuous mark made on some surface by a moving point. It may be two-dimensional, three dimensional or implied. Often it is an outline, contour, or silhouette.

Line

Has five characteristics:Length

• Width• Curvature• Depth• Texture

How is Elaine Coleman using line on this porcelain vase?

Shape

• Formed by lines that enclose a space• Two dimensional, only have a height

and length• Can be geometric or organic • A real or imaginary object defined or

determined by the other elements

Shape

• This painting by Mondrian is mostly comprised of shapes.

How would you describe the use of shape on this piece of Pueblo pottery?

Form

• Three dimensional, has height, length and depth

• Can have one continuous surface or many surfaces.

Form

• Does this sculpture by Brancusi have a continuous surface or is it multi-surfaced?

How could you describe the forms utilized in Christa Assad’s teapot?

Texture

• Texture- refers to the surface quality or “feel” of an object, its smoothness, roughness, or softness. Textures may be real or implied.

Texture

• Is this painting by Van Gogh an example of real or implied texture?

What type of textures do you see in Jack Troy’s tea bowl?

Space• Space is an empty place or surface in or

around a work of art. Space can be two-dimensional, three-dimensional, negative and/or positive.

Positive and Negative Space

Space

• In 3D Art positive space refers to the object itself and negative space is the air that surrounds it.

How does the element of Space affect the way we view this vase by Jennifer McCurdy?

The Principles of Design

• The principles are the different ways artists can use the elements to create unified works of art.

The Principles of Art

• Balance• Emphasis• Harmony• Variety• Movement• Rhythm• Proportion

Balance-

refers to a way of combining elements to add a feeling of equilibrium or stability to a work of art. Balance can be of three kinds : symmetrical, asymmetrical and radial.

Christ Delivering the Keys of the Kingdom to Saint Peter, Sistine Chapel 1481-1483 by Perugino

How would you describe the balance of this sculpture by Megan Puls?

Emphasis

• Using elements of art to develop points of interest to pull the viewer's eye to important parts of the body of the work.

• Isolation of an element

• Placement

Do you see a focal point in this piece by Anna Whitehouse?

• Harmony- refers to a way of combining a similar elements in an artwork to accent their similarities.

• Repetition of shapes and colors can create a sense of harmony.

How did Tom Coleman and Frank Boyden use the elements of art to create harmony in this collaborative work of art?

Variety

• Refers to the differences in the work.• You can achieve variety by using

different shapes, textures, colors and values in your work.

Movement & Rhythm

• Movement-Adds excitement to your work by showing action and directing the viewers eyes throughout the picture plane.

• Rhythm-a type of movement in drawing, painting and sculpture. It is seen in repeating of shapes and colors. Alternating lights and darks also give a sense of rhythm.

Proportion

• Proportion- refers to the relationship of certain elements to the whole and to each other.

Is proportion or scale important in this work by Jim Denevan?

Peter Voulkos

Patrick Crabb

Charlie Riggs

Tom Coleman &Frank Boyden

Paul Soldner

John Mason