Ceramics Glossary
Find definitions for ceramic terms, materials, techniques, and tools.
Discover glossary terms
Pigments and colorantsPigments and colorants are natural or synthetic substances used in ceramics to alter and enrich the color of glazes, engobes or clays. These compounds are added to clay or glaze mixtures to obtain a wide variety of shades, from soft, natural colors to vibrant, saturated tones. Pigments can be derived from naturally occurring minerals, such as metal oxides, or can be chemically manufactured to provide a wider range of colors and effects. The interaction between pigments and firing conditions, including temperature and kiln atmosphere (oxidizing or reducing), determines the final color obtained in the ceramic piece.
The use of pigments and colorants makes it possible to customize the creations, adding depth and complexity to the pieces. Pigments can be applied in various ways, such as mixed in the glaze base, applied directly on the surface of the clay before firing, or used to create specific designs and patterns through painting, silk-screening or stamping techniques. The correct selection and application of pigments is crucial to achieve the desired effect and to ensure the durability and resistance of the color once the piece has been fired.
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.
Spodumene (LiAl(SiO₃)₂)Spodumene is a lithium mineral that is used especially as a flux in the manufacture of ceramic glazes. Its main function is to lower the melting point of glazes, which allows them to melt at lower temperatures and facilitates the creation of more uniform and controlled coatings.
Spodumene is also valuable for its high thermal expansion capability, which makes it an ideal component for glazes used in high-temperature ceramics. This property allows glazes to better withstand thermal shock and reduces the possibility of parts suffering deformation or fracture due to rapid temperature changes.
Sodium feldspar (NaAlSi₃O₈)Sodium feldspar is a mineral used as a flux in the formulation of ceramic glazes and clays. This mineral is especially valuable because of its high sodium content, which helps lower the melting point of ceramic mixtures, allowing them to vitrify at lower temperatures. It also plays a role in the thermal resistance of the pieces, as it helps to reduce thermal expansion and improve dimensional stability during firing.
One of the most appreciated characteristics of sodium feldspar is its ability to contribute to the formation of a smooth, shiny and high quality surface in glazes.
Its use is especially prevalent in mass production ceramics, where energy efficiency and consistency in glaze quality are priorities. In these industrial applications, sodium feldspar helps ensure a more economical and controlled manufacturing process, making it possible to produce large volumes of ceramics without compromising the quality or durability of the pieces.
UlexiteUlexite, also known as "television stone", is a borate-rich mineral used mainly in ceramics as a flux in glazes. Its main function is to lower the melting point of glazes, which allows glossy, well vitrified finishes to be obtained without the need for firing at excessively high temperatures. Ulexite also improves the adhesion of the glazes to the pieces and gives them greater durability.
In addition to being an excellent flux, ulexite can contribute to the creation of unique visual effects on the glaze surface, creating interesting patterns or smooth textures, depending on kiln conditions and the concentration of ulexite in the mixture.
CeladonCeladon is a ceramic glaze known for its characteristic translucent green color, obtained by adding small amounts of iron oxide to the glaze. This distinctive color is produced during firing in a reducing atmosphere, where the iron oxide changes from its oxidized state (Fe³⁺) to its reduced state (Fe²⁺), generating green hues that can range from soft and grayish to intense, depending on the composition of the glaze, the thickness of the applied layer, and kiln conditions.
Celadon is typically applied on stoneware or porcelain ceramic bodies, as these materials allow the glaze to acquire its characteristic translucent appearance. In addition to its unique aesthetics, celadon highlights carved or engraved details on the surface of the piece, as the translucent glaze builds up on the reliefs and creates subtle contrasts.
Although historically associated with green, celadon can vary in hue depending on factors such as the chemical composition of the glaze, kiln temperature and firing atmosphere. These variations include blues, grays and even shades close to amber, depending on the specific process conditions.
Today, celadon remains a popular technique in contemporary ceramics, both artisanal and industrial, appreciated for its combination of simplicity, elegance and visual depth.
PaddlingPaddling is a ceramic modeling technique that consists of delicately striking a piece of clay with a flat tool, known as a palette, which can be made of wood, rubber or even metal. This process allows the shape, profile and surface of the piece to be modified without applying direct pressure with the hands, which facilitates the preservation of symmetry and control of volumes. Upon repeated impact, the trowel compacts, smoothes and molds the clay, creating more defined surfaces, subtle depressions or textures without altering the structural integrity of the piece.
PyrometerThe pyrometer is a fundamental instrument in the control of the thermal cycle of the kiln. Its main function is to convert temperature variations into numerical readings, allowing to adjust the heating curve, the holds (times at constant temperature) and the cooling process. Thanks to this precise control, the kiln's internal atmosphere can be adapted to the needs of the clay body and glazes used, whether it is an oxidizing, neutral or reducing atmosphere.
Throughout the thermal ascent, the pyrometer helps to avoid sudden temperature rises that could cause cracking or internal stresses in the pieces. Similarly, during cooling, proper monitoring reduces the risk of thermal shock. The use of the pyrometer in combination with other indicators, such as pyrometric cones or the color of the kiln interior, provides a complete picture of what is happening during firing, increasing the reproducibility of results and the final quality of the work.
AlmagreAlmagre is a dark red pigment traditionally used to decorate and color ceramic pieces. This pigment, composed primarily of iron oxides, is mixed with clay or glazes to impart a deep, rich tone that highlights details and adds contrast to the decorations on ceramic pieces. Almagre is valued for its ability to produce intense, long-lasting colors that resist fading during firing and use.
In the history of ceramics, vinegar has been an essential component in various ceramic traditions around the world, from Chinese porcelain to Spanish Talavera pottery. Its versatility allows the creation of a variety of visual effects, from finely delineated edges to large areas of uniform color, contributing significantly to the final aesthetics of the pieces.
Dolomite (CaMg(CO₃)₂)Dolomite is a mineral composed mainly of calcium and magnesium carbonate, which is used especially in the manufacture of glazes, as it is an important source of calcium and magnesium, two essential elements in the formulation of ceramic glazes. As a flux, dolomite helps to reduce the melting temperature of glazes, facilitating their firing at lower temperatures. This not only improves the efficiency of the firing process, but also allows for more precise control of glaze texture and appearance.
Dolomite is especially useful in the creation of matte or semi-matte glazes, as it contributes to the opacity and matte finish of the pieces. In addition to its aesthetic properties, dolomite improves resistance to thermal changes, making it a valuable material for utilitarian ceramics, such as tableware and cookware. This characteristic is crucial in pieces that must withstand rapid temperature changes, such as those used in kilns or in contact with hot liquids.
