Saturday, November 13th, 2021

There’s a distinct difference between the words “clay” and “ceramic.” Clay is the raw material extracted from the earth. Natural clay is decomposed igneous rock which ranges in colors, including white, pale gray, light tan, rusty red, brown, or even black. Clay is typically found near a water source and is compressed mud that is thick and gooey, the kind of stuff that you may have stepped in once and almost lost a shoe. The material can be collected to form vessels, but it must be processed (purified) and stabilized for stability and predictability. Once the desired form is achieved, the vessel is then fired until it is vitrified (turning to stone), and then it is technically described as ceramic.

Ceramic Artists and crafters alike make ceramic by manipulating clay through creative processes such as: forming and shaping; firing stages; surface techniques (sgraffito, slip trailing, texturizing), glazing or under glazing (decorating, coating by various techniques); and re-firing (re-baking, to harden the glaze). Potters typically use three primary clay bodies depending on the practice and application – earthenware, Stoneware, Porcelain. Regardless of the body type, Average clay contains about 20% water and 9% organic matter; thus, finished pots (bisque or glazed) weigh almost 30% less than the initial clay weight, known as shrink rate.

Hand Building: Strength and plasticity are major factors in workability. Strength is the ability of the formed clay to hold firmer as the shapes are constructed, handled, and attached without sagging, stretching, or cracking. The grog can either be fine or coarse, depending on the surface qualities the potter wants. Such high additions of grog also result in quicker clay air drying time and a reduction in the possibility of cracking during the drying process. A hand-building project will also need plasticity to be workable. The more extreme the shapes being built (e.g., sharp angles or coiling), the more plasticity the clay will need to have. 

Wheel Throwing: The clay needs to have a high degree of plasticity, low water absorption, and strength as it is manipulated (squeezed, turned, gravity force, pulled, and pushed). The amount of water that is absorbed must have a good balance as too much will cause the form to collapse, while too little can make it difficult to work with. Plasticity is determined by the clay particle size within the clay body's formula. It is the most important feature as it allows the form to be shaped, but the higher this amount is, the greater the shrink rate. To provide strength, the clay body should have 7% - 9% of fine particles, such as grog or sand, that provide structural integrity without grinding your hands off.  

There are three primary temperature ranges. Although there is some slight variation between individual potters, these ranges are generally considered to be

• Low-Fire: Cone 06 to Cone 3 (1850 °F - 2135°F) 

• Mid-Range: Cone 4 to Cone 7 (2160 °F - 2290°F)

• High-Fire: Cone 8 to Cone 10 (2315 °F - 2380°F)

The most commonly found natural clay body, the oldest known to ancient potters, is Earthenware clays. These clays are highly plastic, easy to manipulate, and fire at a low-cone that allows for a vivid color application. A famous clay body that you see in most production potter studios is Stoneware clay bodies, which come in a wide range of firing temperatures– Low, Mid, High. These clays are typically gray when moist and range from light gray and buff to medium gray and brown when fired. The clay body is desired for its durability, plasticity, range in firing options, and is typically good for wheel throwing and hand-building applications. Porcelain clay bodies, which contain a high amount of kaolin, are famous for their white complexion and for having some degree of translucency. The qualities of the clay are excellent for a smooth surface that can be manipulated to be extremely thin, achieving translucency, and pure and vitreous, which gives them their inherent glaze fit quality and unparalleled hardness and durability. However, it is difficult to work with during the throwing stage and cracks and deforms easily during the drying and firing stages because of its low plasticity and density. 

BUT, if you don't have a kiln but still want to incorporate clay making into your classroom or art practice, you can opt for Air-Dry Clay, which dries and hardens naturally at room temperature, usually within 24 hours. Air-dry clay can be used just about anywhere and is excellent for beginners or young children. The media has also become popular among art therapists and physical therapists. Over the years, this clay body has had a bad reputation as they are prone to cracking and crumbling and its fragility and inability to be used for practical purposes. However, a lot of air-dry clays have improved. Air-dry clay is great for mixed media applications as it sticks to various materials like wood, plastic, metal, cardboard, and glass. Air-dry clay can be easily painted with tempera and acrylic and sealed with general-purpose spray paint. You can find these products at just about any hardware store in a range of finishes such as Satin, Matte, Gloss, glitter, and I've even seen glow in the dark! 

Nes's PhilARTsophy © 2021 by Carey Mogianesi is licensed under CC BY-NC 4.0 

In 2008, Graphic artist Shepard Fairey released a poster of newly elected President Barak Obama.

Shortly thereafter, Fairey was sued by an Associated Press photographer for copyright infringement.

The resulting legal proceedings against Fairey demonstrate how quickly simple matters can spin out of control. Read more about this issue of copyright infringement here. 

To see more work by Shepard Fairey, click here.

To understand more about fair use and copyright issues, click here.