Ceramics are integral to our daily lives, found in everything from delicate porcelain teacups to the spark plugs that ignite our car engines. The versatility of ceramics stems from the diverse range of materials that can be used in their creation. These materials dictate the final product’s properties, influencing its strength, porosity, color, and suitability for various applications. Ceramics are tools that exist as the result of combining three expertises. These tools depend on: Understanding clay as a raw material; Having a working knowledge of how to vary fire to harden that clay; Having a working theory of containment. Pottery-making is a series of tradeoffs that requires the ability to successfully negotiate these three technologies. Prehistoric makers of ceramics combined the raw clay materials with a temper—any material that prevents shrinkage when clay is heated up—allowing them to moderate the look, feel, and structural properties of clay. Temper is an integral additive to get the clay to behave in certain ways. Batching in ceramic manufacturing is the mixing of different raw materials into predetermined compounds. The batched materials are then mixed to give the resulting product a more homogeneous and uniform composition.
Traditional Clay-Based Ceramics
Clay, in its various forms, has been the cornerstone of ceramic production for millennia. Earthenware clay has been used by potters throughout history and is probably the earliest form of clay to be used. Earthenware clay is an excellent choice for beginners due to its forgiving nature. There are several slightly different types of clay used for different types of pottery, but clay can be classified into 6 main types that are used commonly among potters. The 6 main types of clay are earthenware clay, stoneware clay, ball clay, fire clay, porcelain clay, and air dry clay. Each type possesses unique properties that make it suitable for specific applications. Earthenware clay, known for its high plasticity and ease of manipulation, is ideal for sculpting, hand-building, and wheel throwing. It’s fired at lower temperatures, resulting in porous and vibrant pieces. Earthenware clay generally matures at a firing temperature of about 950°C and 1,100°C (or 1,745°F and 2,012°F). Earthenware allows for vibrant glazes and sculptural freedom in decorative art. You can learn more about different application methods in this article.
Stoneware clays, prized for their durability and versatility, contain mineral impurities like silica, feldspar, ball clay, and quartz. Stoneware clay is perfect for artists who enjoy creating everyday items like dinnerware, mugs, vases, and other functional pottery pieces. Stoneware provides a broad canvas for various glazes and surface treatments. Typically, the firing range of stoneware clay is much higher than that of earthenware clay (stoneware is fired at a temperature range between 1000°C and 1380°C). It is also sometimes mixed with ball clay and fire clay to increase its resistance to heat and make harder, more resilient pieces. Stoneware is an excellent choice for creating durable, usable functional items. Porcelain clays, often considered the pinnacle of ceramic artistry, are known for their delicate appearance and translucent finish when fired at high temperatures. Kaolin clays are the least plastic clays and are therefore quite hard to work with. Porcelain clay is sometimes known as kaolin as this is what it is made of. Porcelain is highly sought after for its durability, delicate appearance, and elegant finish, though its premium quality often comes at a higher price. Porcelain is preferred for delicate and intricate artworks and fine art pieces.
Ball clays, valued for their workability and firing properties, are typically used in combination with other clays to enhance plasticity and manipulation. Because of the high plastic and high binding quality, Ball clays are commonly used for floor tiles, toilet bowls, vases, and tableware. Fire clay, prized for its exceptional resistance to high temperatures, finds application in the creation of pottery products that demand heat resistance, such as bricks for kilns and ovens. Air-dry clay is a type of clay that dries and hardens naturally in the air without the need for baking or firing in a kiln. Air-dry clay is typically softer and more pliable than traditional ceramics clay. It can be shaped, sculpted, and molded using simple tools. For some inspiration, here’s a list of things to make in pottery class.
Advanced Ceramic Materials
Beyond traditional clays, advanced ceramics utilize materials like alumina, silica, silicon carbide, and zirconia to achieve enhanced properties for specialized applications. For example, silicon nitride and aluminum oxide have high strength and toughness, making them useful in a variety of industrial and engineering applications, such as cutting tools, ball bearings, and diesel engine components. These materials often exhibit exceptional hardness, heat resistance, and chemical inertness, making them suitable for demanding environments. The harsh environment outside of Earth’s atmosphere demands materials that can withstand extreme temperatures, radiation, and the vacuum of space. Lightweight, heat-resistant carbon ceramic composites are used in everything from rocket engines to heat shields, ensuring the success of space missions.
Additives and Property Modification
The properties of ceramic materials can be further tailored through the addition of various additives during the preparation process. These additives can modify plasticity, firing temperature, and the final product’s strength or color. For instance, fluxes are added to glazes to help them melt at lower temperatures. Colourants are metal oxides like cobalt (blue), chrome (green through black), copper (green, blue, even red!), manganese (black, purple and pink) iron (red brown), etc. Wedging your clay is an important step you shouldn’t skip for several reasons. Most importantly, it eliminates any air bubbles that may be in the clay. Wedging also improves its workability giving the clay a more uniform consistency and the same moisture level throughout. The raw materials are prepared for ceramics processing through a number of different techniques. This stage is designed to separate the raw materials from any impurities that may exist and to prepare them for better mixing and forming.
