Ceramics Glossary
Find definitions for ceramic terms, materials, techniques, and tools.
Discover glossary terms
Glazed tileA glazed tile is a thin, flat ceramic tile, usually square or rectangular, used to cover walls, floors or as a decorative element on various architectural surfaces. Tiles are valued for their durability, water resistance and ease of maintenance, making them ideal for areas such as kitchens, bathrooms and exterior facades. In addition, they can be decorated with a wide variety of colors, patterns and designs, allowing the creation of visually stunning mosaics and decorations.
The glazing and glazed tile technique allows for a wide variety of finishes, from matte to glossy, and from solid colors to complex designs with reliefs and textures. Decorative tiles can incorporate three-dimensional elements through the use of bas-reliefs or high reliefs, adding depth and dimension to the surfaces where they are applied.
Bone porcelainBone porcelain is distinguished by its unique composition that includes a significant proportion of calcined bone ash, as well as kaolin, feldspar and quartz. This formula modifies the internal structure of the clay body, providing greater mechanical strength, a soft translucency and a characteristic luster obtained by vitrifying the piece at high temperatures. Its ductility during modeling facilitates the creation of thin pieces and elaborate contours, which makes it especially appreciated for fine tableware, figures and decorative objects.
Although it requires rigorous control of temperature and firing time, its dimensional stability and response to appropriate glazes ensure smooth surfaces and finishes that enhance the brightness of the piece. Moreover, bone porcelain can be used in both artisanal and industrial contexts, offering wide aesthetic possibilities ranging from monochromatic sobriety to the application of complex decorations.
Thermal expansionThermal expansion refers to the expansion that clays, clay bodys and glazes undergo when exposed to heat in the kiln. This phenomenon occurs because the increase in temperature causes increased vibration of the molecules, causing the materials to expand. During firing, this expansion is gradual, but in the cooling stage, the materials begin to contract. The correct understanding of thermal expansion is fundamental to avoid structural defects in ceramic pieces.
If the coefficient of thermal expansion of the glaze does not match that of the clay body, internal stresses occur in the part. These stresses can cause common problems such as cracking, spalling, or fracture. To avoid these problems, glazes and clays with compatible coefficients of expansion must be formulated. Proper choice of materials is especially critical in utility ceramics, where exposure to sudden temperature changes can cause thermal shocks that damage the part.
SuninngSunning refers to the process of exposing a ceramic piece to the sun or an intense light source before or after firing. Prior to firing, sunning helps remove excess moisture from the clay, facilitating more uniform drying and reducing the risk of cracking. This step is crucial to ensure that the piece maintains its shape and structure during the later stages of the manufacturing process.
After firing, sunning can be used to highlight the colors and textures of the glaze, as exposure to sunlight can intensify certain tones and create unique visual effects. In addition, sunning ceramic pieces can be part of sustainable practices, harnessing the sun's natural energy for drying and cooling the pieces, thus reducing energy consumption in the production process.
Calcium borate (CaB₄O₇)Calcium borate is a ceramic compound used mainly as a flux in ceramic glazes. Its main function is to facilitate the melting of the ingredients at low and medium temperatures, which allows the glaze to melt more efficiently. It also improves the transparency of glazes and contributes to the creation of smooth and glossy finishes. Its ability to stabilize the ceramic mixture is essential, as it prevents the glaze from becoming excessively fluid or sliding off the surface during firing, ensuring uniform adhesion.
Calcium borate is particularly useful for creating transparent glazes that allow painted or sgraffito decorations to stand out beneath the glazed surface. This is because its fluxing action not only improves the quality of the finish, but also brings out the details and colors of the applied artistic decorations. In addition, calcium borate helps to reduce the risk of cracking or discoloration in ceramics.
CarborundumCarborundum, also known as silicon carbide (SiC), is an extremely hard material used in ceramics for polishing, grinding and finishing processes. Its exceptional hardness, comparable to that of diamond, makes it an essential tool for smoothing rough surfaces on ceramic parts, especially after bisque-firing or before final firing. This ensures that the pieces are free of imperfections, improving both their aesthetics and the adhesion of the glaze.
In handmade ceramics, carborundum is especially useful for removing burrs or rough areas on bisque-fired pieces before glazing. It is also widely used in the manufacture of abrasive tools such as sharpening stones, cutting discs and sandpaper, which are essential for working with high-density ceramic and refractory materials.
Ribbed or groovingGrooving in ceramics is a decorative technique that involves creating channels or grooves in the surface of a piece to add texture, relief and aesthetic detail. These channels can be carved directly into the clay prior to glazing or can be formed by applying engobes, glazes or clay bodys in specific patterns. Grooving not only enhances the visual appearance of the piece, but can also add functionality by providing additional grips or improving the ergonomics of cookware.
This technique allows ceramists to experiment with different designs and patterns, from straight, geometric lines to organic, flowing shapes. Ribbing can be used to highlight specific features of a piece, such as the flage of a plate or the body of a pitcher, creating a dynamic interplay between light and shadow that enhances the depth and dimensionality of the work.
Sodium Carboxymethyl Cellulose or CMCSodium Carboxymethyl Cellulose, or CMC, is an organic additive derived from cellulose, widely used in ceramics due to its highly versatile properties. This compound is mainly used to improve the plasticity, cohesion and workability of clay bodys, which facilitates the formation of more consistent and easier to handle pieces. When incorporated into clay bodys, CMC helps to improve water holding capacity and flexibility, preventing the pieces from cracking or deforming during the drying process.
In glazes and engobes, CMC plays a key role in viscosity control, allowing for a more precise and uniform application of coatings. Because of its ability to increase viscosity, it prevents glazes and engobes from becoming too liquid or slipping off surfaces. In addition, CMC helps to maintain the suspension of particles in the slips, preventing them from settling, which ensures greater consistency in the mixture during the application process.
Brushing, Application byBrushing is a decorative technique that allows the application of engobes, glazes, oxides or pigments with a brush or similar tools to create detailed designs, complex patterns or abstract effects. It is a very versatile technique, used on both utilitarian and artistic pieces, and can be done on raw, bisque-fired or glazed pieces.
Brushing offers almost unlimited creative freedom. Depending on the type of brush used, it is possible to achieve fine, precise strokes or more expressive, fluid effects. It is also ideal for working with multiple colors, applying layers that can blend into each other or remain defined after firing.
The success of the brushing depends on the consistency of the material applied, as well as the control of the stroke and the absorption of the surface. On raw pieces, painted engobes integrate directly with the clay, while on bisque-fired or glazed pieces, the effect may vary depending on the firing.
FretworkCeramic fretwork is a decorative technique that consists of perforating patterns or designs on the surface of a ceramic piece. This method creates translucent areas that allow light to pass through, adding a visual and tactile dimension to the piece. Openwork can be done with specialized tools that cut or perforate the clay before firing, or by applying molds that leave impressions on the surface.
This technique not only beautifies ceramic pieces, but can also serve to reduce the weight of the piece without compromising its structural integrity. Openwork is commonly used on vases, plates, lamps and other decorative objects, allowing the creation of intricate patterns that stand out for their delicacy and precision. In addition, fretwork can be combined with other decorative techniques, such as glazing or beveling, to achieve more complex and customized finishes.
