Ceramics Glossary
Find definitions for ceramic terms, materials, techniques, and tools.
Discover glossary terms
High reliefHigh relief is a sculpting technique applied to ceramics that consists of creating decorations that protrude significantly from the surface of the piece, providing a marked three-dimensional dimension. Unlike bas-relief, where figures or patterns are slightly sunken, high relief stands out for its prominence and depth, allowing details to be clearly visible and tactile. This technique is used to add elaborate decorative elements, such as human figures, animals, floral or geometric motifs, which enhance the aesthetics and artistic value of the ceramic pieces.
High relief requires great precision and skill on the part of the ceramist, as the protruding elements must be kept uniform and well balanced to avoid structural imbalances in the piece. In addition, during firing, it is crucial to control the kiln conditions to ensure that the relief areas are properly vitrified without warping or cracking, thus preserving the integrity and beauty of the details.
Nepheline syeniteNepheline syenite is a rock composed mainly of feldspar and nepheline, minerals rich in aluminum and silica, which is used as a flux. This naturally occurring feldspar contains abnormally high amounts of alkali, particularly sodium and potassium, relative to its silica and alumina content. As a result, it has a lower melting point than other feldspars, making it a desirable substitute when a lower maturation range is required in firing, both for clay bodys and in frits and glazes. Despite this lower maturation range, nepheline syenite manages to maintain a quality similar to that of feldspar, providing the same translucency and mechanical strength in ceramic products.
An important factor in the effectiveness of nepheline syenite as a flux is its grain size, which has a great influence on its melting properties. The finer the grain of nepheline syenite, the greater its influence as a flux, which facilitates the creation of more homogeneous glazes with better aesthetic and mechanical characteristics.
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.
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.
AirbrushAn airbrush is a tool that is connected to an air compressor and is used to apply glazes, engobes or any other type of coating on the surface of ceramic pieces. Through controlled spraying, the airbrush allows a smooth and uniform application of the material, which facilitates obtaining fine and detailed finishes.
This technique is especially useful for creating visual effects such as color gradients, soft shading or thin layers of glaze that do not build up excessively. In addition, it is ideal for both large-scale work, such as sculptures, and precision work, allowing delicate details without the need for multiple layers.
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.
InlayInlaying is a decorative technique that involves inlaying small pieces of contrasting material, such as different colored clay or ceramic shards, into the surface of a piece before firing. These inlays are smoothed and integrated with the surface to create patterns, reliefs or textures. Once fired, the piece presents a decorative design in which the inlaid materials are highlighted by their color or texture.
This technique is especially popular in artistic ceramics, where it is used to create striking visual effects and color contrasts. It is also found in traditional pieces, such as decorative tiles or utensils with geometric patterns.
Slab techniqueThe slab technique, also known as slabs or slabs, consists of flattening the clay into uniform slabs that are then cut and assembled to create geometric shapes or flat structures. This method is done using rollers, presses or molds to obtain slabs of clay with a consistent thickness. Once flattened, the clay slabs are cut with sharp tools and assembled by applying slip to create strong, homogeneous joints.
This technique is especially useful for creating boxes, tiles, and other angular shapes that would be difficult to achieve by pottery wheel or hand modeling. The slabs also facilitate the creation of reliefs and textures applied directly to surfaces, allowing for greater precision in details and finishes. In addition, this technique is ideal for mass production of parts with repetitive shapes, ensuring uniformity in design and construction.
TemplateThe template is an essential tool in ceramic work, designed to facilitate the creation of consistent and precise shapes. Usually made from materials such as cardboard, wood, plastic or metal, the template serves as a guide for trimming or shaping clay into specific forms during techniques such as plate modeling, hand building or even the pottery wheel. It is also used to ensure that the components of a part, such as the walls of a vase or the panels of a box, have uniform dimensions.
Templates are not only functional in the structural construction of parts, but are also valuable in decoration. In techniques such as stenciling, templates allow repetitive designs to be applied with precision, using engobes, glazes or even textures. In addition, custom stencils provide the freedom to explore unique shapes and patterns that can become a hallmark of your work.
In mass production, templates are especially useful for ensuring uniformity between parts, reducing errors and optimizing working time. They are a versatile tool, as they can be easily adapted to specific projects by simply adjusting their size or shape.
IshihazeThe term Ishihaze, from Japanese, translates as "broken rock or stone" and refers to a decorative and textural effect that occurs on the surface of ceramic pieces, especially in high-temperature glazes. This effect is characterized by the appearance of small bumps, fissures or irregularities reminiscent of the texture of a broken or worn stone. Ishihaze is not just an accidental imperfection, but, in many cases, is intentionally sought after as part of the wabi-sabi aesthetic, which celebrates the beauty of the imperfect and the natural in Japanese art.
This effect can be generated in a number of ways. It often occurs due to the inclusion of coarse particles or impurities in the clay or glaze mixture, which during firing react unevenly, creating small elevations or breaks in the surface. It can also be due to the use of glazes with uneven shrinkage properties, which causes certain areas to tighten and generate rough or cracked textures.
