Learning Pottery: The 50 Most Important Technical Terms for Beginners (Glossary)

Hardly any hobby is as full of technical jargon as pottery. In your first class, terms like leather-hard, grog, craquelé, or Cone 6 will be thrown at you, often without being explained in any detail.

At Formwerk Pottery Supplies Berlin, we advise beginners every day who face the same problem. They want to buy supplies, choose a kiln, or understand a glaze, and they stumble over a technical term every other word. This glossary is our answer: 50 key pottery terms, sorted alphabetically, clearly and concisely explained.

A

Abdrehen (Trimming). The post-processing of a piece thrown on the wheel. Once the clay is leather-hard, the piece is placed upside down on the wheel again, and excess clay at the base is removed using a ribbon tool. The result: a clean foot, uniform wall thickness, and a light, elegant shape. Without trimming, many thrown pieces appear chunky at the bottom. You can find suitable ribbon tools and trimming equipment in our tool assortment.

Trimming on the pottery wheel

Aufbauen (Handbuilding). A collective term for all pottery techniques that do not use a pottery wheel. Classic methods include coiling, slab building, and pinch potting. Handbuilding is the oldest pottery technique known to humanity; the wheel was invented much later. For beginners, this is often a better starting point than wheel throwing because you can hold a finished piece in your hands more quickly.

Aufglasurfarbe (Overglaze color). Color applied to the already finished, glazed surface after the glaze firing and then fired a third time at a lower temperature (usually 750 to 850 °C). It allows for very fine, precise painting, common in porcelain decoration. The disadvantage: Overglaze colors are not as scratch-resistant as colors applied under the glaze.

B

Biskuitbrand (Bisque firing). Synonym for the first firing, in which the clay is transformed into a solid but still porous state. Also called raw firing or preliminary firing. Usually takes place between 900 and 1,000 °C. See details and costs in our article What is a bisque firing?

Brennkurve (Firing curve). The progression of temperature over time during a firing, usually shown in a diagram: heating, holding (soaking), and cooling. A well-programmed firing curve is one of the most important factors for consistent results. Modern kiln controllers like the Bentrup TC66 can store multiple curves and make programming significantly easier.

The electronic TC66 controller from the manufacturer Bentrup.

Brennplatte (Kiln shelf). A heat-resistant shelf on which pieces are placed inside the kiln. It consists of high-temperature ceramic materials and must be treated regularly with a kiln wash (see "Trennmittel") so that runny glaze does not damage the shelf. You can find suitable kiln shelves, supports, and kiln wash in our accessories section.

C

Cone. A small ceramic pyramid that melts at a defined temperature. Originally developed to monitor the firing process without a thermometer. Today, it is mostly used as a temperature indicator: Cone 04 = 1,063 °C (bisque firing), Cone 5 = 1,186 °C, Cone 6 = 1,222 °C, Cone 10 = 1,305 °C (high firing). You can find the complete table in our article Pyrometric Cone Values.

Depending on the temperature, the cones melt differently, helping the potter to better track the development of the heat inside the kiln.

D

Daumendrucktechnik (Pinch pot technique). Perhaps the simplest handbuilding technique. A small bowl is formed from a ball of clay solely by pressing in with the thumb. It is classically the first exercise in many pottery courses because it requires no tools and provides a direct feel for the material.

Drehscheibe (Pottery wheel). A rotating device used for shaping clay. There are two types: the manual kick wheel (powered by foot) and the electric wheel (operated with a foot pedal). For beginners, an electric wheel is almost always recommended, as the distribution of force is easier to control. You can find detailed buying advice in Buying a pottery wheel: Which one suits your working style?, and the latest models in our pottery wheel assortment.

E

Einbrand (Single firing). A less common alternative to the classic two-firing process. The clay is glazed directly and fired only once to its final temperature. It saves energy and time, but is technically demanding. The glaze layer must be precisely tuned to the state of the clay, otherwise it will flake off during heating. Not recommended for beginners.

Engobe (Slip). Colored liquid clay applied to leather-hard or dry clay that fuses firmly with the body during firing. Unlike glaze, the surface of an engobe remains matte and slightly porous. It is excellent for painting, patterns, and inscriptions. It is often covered with a clear overglaze to make it waterproof.

F

Feuerfestigkeit (Refractoriness). The ability of a material to withstand high temperatures without deforming, melting, or decomposing. Fireproof materials include, for example, the lining of the kiln, kiln shelves, and kiln supports. For the clay body itself: the higher the temperature at which the clay sinters (see "Sintern"), the more refractory it is.

Fluss (Flow). Describes the behavior of a glaze during firing: how much does it move? Very fluid, or runny glazes, like many of the AMACO Potter's Choice glazes, create dramatic dripping and depth effects, but require a gap at the bottom of the piece to prevent them from running onto the kiln shelf. Not to be confused with the chemical meaning of flux in glaze recipes.

Fritte (Frit). A pre-melted, then solidified glass material that serves as a base in many glazes. Frits are chemically more stable and less toxic than the individual raw materials used to create them. Therefore, many modern glazes are frit-based. Not directly relevant for beginners, but the term often appears in glaze recipes.

G

Glasur (Glaze). A thin, glass-like layer applied to the bisqued piece and melted during the glaze firing. It makes ceramics waterproof, hygienic, and decorative. They come in countless formulations: matte, glossy, transparent, opaque, reactive. A good introduction to the basics is our article Understanding Glazes: Types, Application, and Common Mistakes. You can find all the glazes available from us in our glaze assortment.

Glazes are generally liquid and are applied with a brush as brushing glazes. Here is an example, the Iron Yellow glaze from the US manufacturer Amaco.

Glasurbrand (Glaze firing). The second firing after the bisque firing. Depending on the type of clay and glaze, it takes place between 1,040 and 1,280 °C. During this phase, the glaze melts and bonds firmly with the ceramic body. Unlike the bisque firing, pieces must not touch each other; glaze that has bonded pieces together is irreparable.

Grünware (Greenware). Unfired, dry or semi-dry clay that has not yet been through the kiln. Extremely fragile. A small bump and the work is ruined. Therefore: always transport greenware carefully and never let it get wet, or the clay will dissolve.

H

Haltezeit (Soaking time). The time during which the target temperature is kept constant during a firing, usually 10 to 30 minutes at the end of the heating phase. It ensures that the heat is distributed evenly throughout the kiln and that all pieces are thoroughly fired. Without soaking time, the center of the kiln often fires differently than the edges.

Handaufbau (Handbuilding). A collective term for all techniques where clay is shaped without a wheel, i.e., coiling, slab building, and pinch potting. Handbuilding is more beginner-friendly than wheel throwing, allows for organic, individual shapes, and does not require expensive equipment. Many professional studios work exclusively with handbuilding.

I

Irdenware (Earthenware). Ceramics fired at low temperatures (900 to 1,100 °C). The body remains porous and is only waterproof if glazed. Classic for flower pots, Mediterranean terracotta, and historical utilitarian ware. Not frost-resistant; earthenware pots left outside in winter will almost always crack.

K

Kaolin (China clay). Pure, white-firing clay mineral, the main ingredient in porcelain. Kaolin is not very plastic (difficult to shape) but extremely high-firing (up to over 1,400 °C) and provides the characteristic white base color. The name comes from the Chinese mountain Gaoling, where kaolin was first discovered.

Kneten (Wedging). Preparing the clay before work. Goal: remove air bubbles, distribute moisture evenly, and make the clay supple again. More important than many think—poorly wedged clay can explode in the kiln. The classic spiral wedging technique is reminiscent of kneading bread dough.

Knochenhart (Bone-dry). The state of clay when it has dried completely, like an old, bleached bone. No moisture content left, no plastic formability. Only in this state can the clay be placed in the bisque firing, otherwise it will explode due to residual moisture evaporating. How long this takes is explained in our article How many days should clay dry before firing?

Krakelee (Crazing). A fine network of cracks in the glaze caused by the different expansion behaviors of the clay body and the glaze. It can be a flaw (it is unhygienic in functional ceramics because bacteria can enter) or an intentional design feature (classic in Raku and Hagi ceramics). Some potters rub ink into the craquelé to accentuate it.

L

Layering. The practice of layering multiple glazes to create complex color and flowing effects. Particularly popular with the AMACO Potter's Choice series, which was explicitly developed for layering combinations. Basic rule: apply the bottom layer in 2 coats, the top layer in 1 to 2 coats, and apply the top glaze more thinly on the upper third. Explained in our AMACO Potter's Choice Guide, with all 70 colors in our glaze assortment.

Leather-hard. The condition of clay between freshly shaped and bone-dry. Firm enough that the piece holds its shape, but still moist enough to carve, paint, or attach handles. The most important state of work for hand-building techniques and finishing. Leather-hard is recognized by the fact that the clay feels cool and a light mark remains when pressed with a fingernail.

M

Loop tool. A loop-shaped metal tool with a wooden or plastic handle, used for removing clay. Especially useful when trimming on the potter's wheel or carving out shapes in hand-building. Available in various sizes and shapes: round, oval, pointed, straight. One of the most used tools in every pottery studio. You can find more tools in our article The 30 Most Important Pottery Tools, and suitable loop tools in our tool assortment.

O

Oxidation (Oxidation firing). Firing in an oxygen-rich atmosphere, as in any standard electric kiln. Metal oxides in clay and glaze retain their high oxidation state: iron appears brownish-yellow, copper greenish. The opposite is reduction (see entry). Almost all hobby potters work with oxidation firing because it happens automatically in an electric kiln. You can find our range of electric kilns from Kittec and Pyrotec in the shop.

P

Slab building. A hand-building technique where clay is rolled into uniform slabs and then joined together to create shapes. Ideal for geometric objects: angular vases, bowls, tiles, boxes. The slabs are usually joined in a leather-hard state, glued with slip, and the edges are roughened to ensure the connection holds.

Porosity. The proportion of open pores in the fired ceramic body (bisque). Visible in how much water a piece absorbs. After the bisque firing, porosity is high (which is why the body absorbs glaze). After the glaze firing at high temperatures, the stoneware body is almost non-porous, with water absorption of less than 3%. Earthenware always remains porous.

Porcelain. The most refined and highest-firing type of ceramic, consisting mainly of kaolin, feldspar, and quartz. Fired at 1,280 to 1,450 °C, it is white, dense, and translucent. Demanding to work with because it is less plastic and prone to cracking. Not the best starting point for beginners.

R

Raku. A Japanese firing technique in which the glowing piece is taken directly out of the kiln and placed in sawdust or straw. The oxygen deprivation and thermal shock create unmistakable crackle patterns and deep black reduction areas. Historically closely linked to the Japanese tea ceremony. Details in our article Raku Pottery: What is it?

Example of a mug fired using the Raku technique.

Reduction (Reduction firing). Firing in an oxygen-poor atmosphere, only possible in gas or wood kilns. In the final phase, the oxygen supply is actively throttled so that metal oxides in the glaze release oxygen. This causes iron to turn deep red or black, and copper to appear red or violet. Classic for Tenmoku, Celadon, and Oxblood glazes. Some modern glaze series, like AMACO Potter's Choice, chemically reproduce this look without actual reduction. This is then referred to as reduction effects in oxidation.

Raw ware. Unfired, dried clay; a synonym for greenware. Some studios make a more precise distinction: greenware is very fresh and still moist, raw ware is dry before firing. In everyday life, both terms are often used synonymously.

S

Grog (Chamotte). Fired, ground clay used as an additive in clay bodies. It increases stability (pieces hold their shape better), reduces shrinkage and cracking, and makes the clay easier to handle. Distinguished by grain size: from fine (0 to 0.2 mm) to coarse (0.5 to 2 mm). Grogged clays are the first choice for large pieces, hand-building, and for anyone who likes a textured surface. You can find various grogged clay types in our pottery clay assortment.

Ceramic body (Scherben). The fired clay object. Not to be confused with "shards" in the sense of broken pieces. Potters say "the body is dense" (meaning: well-fired) or "a white body" (meaning: light stoneware). The technical term refers to the material after firing, not broken debris.

Slip. Thinly mixed clay with a high water content. Used in several contexts: for joining leather-hard clay parts (attaching handles, connecting slabs), as a casting slip for plaster molds (slip casting), or as a colored slurry for painting (called engobe).

Bisque firing. The first firing. Transforms dried clay into a firm but still porous body that can then be glazed. Usually between 900 and 1,000 °C. Also called biscuit firing or pre-firing.

Sintering (Sinter). The process by which clay particles bond together at high temperatures without completely melting. The result is a dense, hard body. Stoneware and porcelain are fired past the sintering point, which is why they are watertight. Earthenware is fired below this point and remains porous.

Earthenware (Steingut). Ceramics fired at low to medium temperatures (1,050 to 1,150 °C) with a porous, white or light body. Only watertight with glaze; otherwise similar to terracotta. Classic for everyday tableware and mid-range tiles. Despite the similar name, it is ceramically very far from stoneware (see below).

Stoneware. Ceramics fired at high temperatures (1,200 to 1,300 °C) with a dense, sintered body. Watertight even without glaze, very robust, frost-proof. The classic choice for utility tableware from studios and manufactories, from coffee mugs to salad bowls.

T

Terracotta. Italian for "baked earth." Refers to unglazed, red-firing earthenware, classic Mediterranean flower pots, amphorae, and historical sculptures. Porous body, reddish-brown color (due to high iron content), not watertight. To make it watertight, terracotta is often coated with a clay slip suspension and fired slightly higher.

Clay. The raw material of pottery. Chemically: a fine-grained sedimentary rock consisting of phyllosilicates that becomes plastically deformable with water. There are hundreds of different clays with varying properties: firing temperature, color, plasticity, grog content. For beginners, we recommend grogged stoneware as a versatile all-rounder. You can find our complete assortment in the pottery clay assortment.

Potter's wheel. Synonym for wheel, the rotating tool for shaping clay. The term is widely used for both manual and electric versions in practice. You can find current models in our potter's wheel assortment.

Kiln wash. A refractory coating, usually a mixture of aluminum oxide and kaolin, applied to kiln shelves so that melted glaze does not stick to the shelf. Must be renewed regularly if the layer shows cracks or flakes off. You can find suitable kiln wash and spare parts in our kiln accessories section.

U

Underglaze. Color applied to the bisque-fired body and subsequently covered with a clear glaze. Fired during the glaze firing. Result: the color is protected under the glaze, is extremely scratch-resistant, and food-safe. Classic choice for painted tableware because it is durable and dishwasher-safe.

W

Wabi-Sabi. A Japanese aesthetic concept that acknowledges beauty in the imperfect, impermanent, and simple. In ceramics, this is reflected in asymmetrical shapes, visible fingerprints, broken glazes, and firing marks—features that make a piece unique.

Coil building. A hand-building technique where clay is rolled into uniform ropes ("coils") and stacked layer by layer. After each layer, the transitions are smoothed out to create a continuous vessel. One of the oldest pottery techniques in human history and ideal for round vessels, vases, and bowls without a wheel.

Z

Centering. The first and most important step when throwing on the potter's wheel: the clay is pressed and shaped on the wheel until it rotates exactly in the center. Without perfect centering, nothing else works; the clay wobbles, the walls become uneven, and the piece cracks. Centering is the first major hurdle every beginner must overcome. Many courses dedicate their entire first session to centering.

Intermediary firing. An additional, often third firing between the bisque and glaze firings, for example after applying an engobe that needs to be consolidated before glazing. Not necessary for every project, but can be useful for complex decorative techniques. Increases time and energy expenditure but provides maximum design freedom.

Frequently Asked Questions

What is the difference between clay and ceramics?
Clay is the raw material, i.e., the moist, plastically deformable substance used for shaping. Ceramics is what it becomes once it is fired. As soon as you put your dried clay piece in the kiln and it hardens, the clay turns into ceramics—irreversibly.

What exactly does leather-hard mean?
Leather-hard is the state between freshly shaped and bone-dry. The clay holds its shape but still feels cool and moist. A light mark remains when pressing with a fingernail. In this state, you can carve your piece, work on it with tools, attach handles, or paint with engobe.

What is the difference between glaze and engobe?
Both are applied to the clay, but they function differently. Engobe is a colored clay slurry. It remains matte and slightly rough, usually applied to leather-hard clay. Glaze is a glass-like coating. It melts during firing and becomes glossy or matte, usually applied to bisque-fired pieces. Both can also be combined.

Why is pottery fired twice?
The first firing (bisque) makes the clay firm but still porous. This is important so that the glaze adheres properly during the second firing. If the body were already dense, the glaze would flake off. Two firings are the classic, forgiving way. Detailed in Can you fire ceramics twice?

 

Conclusion: Vocabulary as a tool

At first glance, pottery terms can seem like an unnecessary hurdle, as if the craft were intentionally made mysterious. In fact, most terms are simply craft vocabulary: precise names for states, techniques, and materials that also need to be precisely distinguished. Once understood, you can communicate fluently in any studio in the world.

This glossary covers the core terms you will encounter in courses, professional literature, and online forums. If you want to dive deeper, you will find individual articles on many of these terms in our blog; we have added the appropriate link in almost every entry.

If you are just starting out and wondering what you actually need to practice pottery at home, we recommend our article How expensive is pottery as a hobby? as a starting point. You can get started right away with our complete assortment, which covers everything from clay, tools, and glazes to kilns. And if any questions remain, feel free to contact us directly—we are happy to advise you.

Note: This glossary is intended to provide a practical introduction and does not claim to be academically exhaustive. Technical terms evolve with practice, and regional differences in terminology are possible. For more in-depth definitions, we recommend the glossary of the Keramikinstitut as a supplementary professional resource.

The Formwerk Berlin team wishes you success with your pottery