Ceramics Glossary
Find definitions for ceramic terms, materials, techniques, and tools.
Discover glossary terms
Cobalt carbonate (CoCO₃)Cobalt carbonate is an extremely powerful and concentrated ceramic colorant, mainly used to produce intense blue tones in glazes and engobes. It is one of the most stable and reliable pigments, capable of resisting high temperatures and atmospheric variations in the kiln, maintaining its color with great precision. Its application adapts to various ceramic techniques, and in small quantities it can even dye other base colors blue.
Cobalt carbonate is one of the most desirable pigments in ceramics because of its ability to create deep and vibrant blue tones, from sky blue to navy blue. Its versatility allows it to generate varied visual effects, such as speckled hues, glazes and high gloss glazes, depending on the mixture and application technique.
This pigment has been used since the 8th century in Persia and China, and its impact on historical ceramics has left a lasting impression, visible in the famous blue and white porcelains of the Ming dynasty and in European majolica.
Firing chamberThe firing chamber is the internal space of a kiln where the pieces are placed to be subjected to high temperatures, transforming the clay into ceramic. This space is designed with refractory materials that resist extreme temperatures and ensure uniform heat distribution, which is crucial to avoid defects such as deformations, cracks or unevenness in the fired pieces.
In electric, gas, wood-fired or industrial kilns, the firing chamber can vary in size, shape and configuration, depending on the type of kiln and its purpose. Generally, it includes shelves and refractory supports that allow pieces to be stacked at different levels, optimizing the available space.
The firing chamber is essential in ceramics, since critical processes such as the elimination of organic matter, vitrification of glazes and stabilization of the pieces take place inside it. Its design and operation are decisive to guarantee the quality, uniformity and durability of the finished ceramic products.
Magnesium carbonate (MgCO₃)Magnesium carbonate is a ceramic additive valued for its ability to modify the texture, appearance and properties of glazes. It is primarily used to achieve matte and opaque finishes, which create less reflective, soft-touch surfaces, ideal for a rustic or natural look.
In addition, magnesium carbonate reduces the viscosity of the liquid glaze, facilitating uniform application in techniques such as airbrushing and dipping. It is also combined with other fluxes and opacifiers to produce visual effects and complex textures, making it a common ingredient in earthenware, stoneware and decorative pieces seeking a unique and sophisticated finish.
Opaque (Glaze)An opaque glaze is one that, thanks to the addition of opacifiers, does not allow to see through its surface, thus hiding the clay underneath. Unlike transparent or semi-opaque glazes, these generate a uniform and solid chromatic coverage, highlighting the colors of the glaze and preventing the tonal variations of the clay body from affecting the final result.
Historically, the development of opaque glazes, particularly white glazes, was motivated by the desire to imitate the aesthetics of Asian porcelain, famous for its purity and luminosity. Islamic and European Renaissance cultures found in opaque glazes an ideal base for applying polychromatic decorations, intensifying contrast and enhancing hand-painted details. Today, opaque glazes are used both in industrial production and in artisan workshops, as they are useful to uniform the finish, hide imperfections in the clay and simplify the application of decorations.
Naked rakuNaked raku is a decorative technique that creates unique, abstract patterns on the surface of ceramic pieces. In this method, the pieces are coated with a layer of engobe or sacrificial glaze that cracks and peels off during the reduction process, leaving black marks on the areas exposed to the smoke. This effect is achieved without the sacrificial glaze permanently adhering to the piece, resulting in a matte, textured surface with a natural finish.
Naked raku is prized for its unpredictability, as patterns depend on the type of slip, reduction time and exposure to fire. This technique is especially popular with ceramists who seek to explore the relationship between control and chance in their pieces.
PotteryPottery is the discipline and art of creating ceramic objects by molding and firing clay. This practice includes the manufacture of a wide range of pieces, from utilitarian utensils and containers to decorative and sculptural works of art. Pottery encompasses diverse techniques such as Throwing, hand modeling, pressing and the use of molds, allowing potters to express their creativity and technical skills in the creation of unique and functional pieces.
Pottery not only has a practical value in providing necessary objects for everyday use, but also has a deep cultural and artistic significance. Throughout history, different cultures have developed distinctive pottery styles and traditions that reflect their values, beliefs and social contexts. Contemporary pottery continues to evolve, incorporating new techniques, materials and artistic concepts to expand the possibilities of ceramic art.
RakuRaku is a traditional Japanese ceramic firing technique characterized by its speed and unique glaze effects. Developed in Japan during the 16th century, raku is primarily used to create tea bowls, but its application has expanded to a variety of decorative and utilitarian ceramic objects. This method involves rapid firing at very high temperatures, followed by abrupt cooling, sometimes in combustible materials such as sawdust, paper or dried grass.
During raku firing, the ceramic pieces are removed from the kiln while still extremely hot and, upon contact with the flammable materials, combustion occurs, generating a momentary reducing atmosphere. This rapid, localized atmosphere causes the metal oxides in the glazes to react differently, creating metallic finishes, crackles and unpredictable color variations that are highly valued for their unique beauty and craftsmanship.
The raku process not only alters the color and texture of the glaze, but also introduces elements of controlled imperfection that reflect the Japanese wabi-sabi aesthetic, which celebrates the beauty of the imperfect and ephemeral. Each raku piece is therefore unique, with patterns and textures that vary slightly from batch to batch, adding artistic and personal value to each creation.
GrogGrog is a type of refractory clay that has undergone a high-temperature firing process to transform it into a more heat-resistant substance. After this process, grog is crushed into fragments of different sizes, from fine to coarse, and added to the clay body in order to improve several of its physical and thermal properties. One of the key functions of grog is to increase the strength of the clay body by reducing shrinkage during drying and firing. This is especially useful in the creation of large and complex pieces, such as sculptures.
In addition, grog is instrumental in improving the body's ability to withstand thermal shock, making it an essential ingredient for the manufacture of ceramics that will be exposed to sudden changes in temperature.
Another important benefit of grog is that it provides a rough texture to the clay body, which makes it an option for texturing the surfaces of the pieces. This rough texture is not only aesthetic, but can also influence the durability and functionality of the pieces, facilitating the adherence of glazes or engobes.
LepidoliteLepidolite is a lithium-rich mineral that is used in ceramics primarily as a flux, playing a crucial role in lowering the melting point of glazes, allowing them to vitrify at lower temperatures. Lepidolite is especially useful in the manufacture of low-temperature ceramics, such as earthenware, where complete vitrification is required without the need for extremely high temperatures.
In addition to its properties as a flux, lepidolite has the ability to modify glaze colors, producing clayl shades. Colors derived from lepidolite can include shades such as pinks, lilacs, pale greens or soft blues, which are difficult to obtain with other fluxes without the need to subject the pieces to high temperatures. In particular, lepidolite is used to obtain translucent glazes that provide a soft and luminous finish to ceramic pieces.
Clay for 3D Printing3D printing clay is a specially formulated mixture for use in 3D printers working with pasty materials, such as clay. This clay combines refined clay with specific additives that improve its plasticity and cohesion, allowing it to pass through the printer nozzles without clogging. Its composition is designed to maintain the shape of the parts immediately after extrusion, preventing them from deforming during initial drying.
This clay is ideal for creating complex parts with geometries that would be difficult to achieve using traditional techniques. Its use has revolutionized contemporary ceramics, allowing artists and designers to experiment with intricate structures, such as three-dimensional patterns and parametric designs.
