EAN

$21.99 Canada $24.99www.barronseduc.com

ISBN: 978-1-4380-0409-9

Collapsing forms Ensure clay is fit

for purpose

Avoiding spout twistIt’s all about the

throwing technique

Even dryingEssential to prevent warpage

Perfect fitting lidsMake lid and body at the same time

No-crack handlesEnsure equal clay consistency for body and handle

Prevent blisteringCheck placement in kiln to avoid excessive heat

The thing about clay is that it does not always behave as you imagine it should. There is not a potter alive who has not encountered problems in the ceramic process at some time. Many would say that only by making and resolving mistakes can you really learn the craft. But wouldn’t it be wonderful if there was a resource that could help you identify where you’d gone wrong and suggest some foolproof ways to fix it?

This comprehensive, down-to-earth manual, created by master ceramicist Jacqui Atkin, is the answer. Inside, potters will discover how common problems arise and learn foolproof solutions for fixing them.

Organized into sections that list issues according to their nature—from preparing clay, to glazing and firing—readers will find methods for dealing with just about every issue imaginable!

Clay too wet | Clay too dry | Not plastic enough | Too plastic | Air in the clay | Mold in/on the clay | Splitting seams |

Out-of-true | Collapsing shape | Uneven thickness | Flaring | Uneven rims | Uneven shape | Uneven clay wall |

Exploding join | Uneven slabs | Surface cracking on slabs | Misshapen slabs | Wobble | Undermining | Closing

cylinders | Teapot spout and handle twist | Pinholing | Wreathing | Casting spot | Flabby casts | Brittle casts |

Livering | Bad draining | Slow casting | Low green strength | Scumming | Uneven drying | Surface cracks |

Base S cracks | Cracks at rims, edges | Spiral cracking | Handle cracks | Dunting | Lime popping | Blow

out | Bloating | Blistering | Low-fired strength | Specking | Warping | Flaking | Glaze too thick | Glaze

settling | Overlapping | Chittered edges | Runs | Dribbles | Patchy glazing | Streaking | Bittiness |

Crawling | Crazing | Milky transparent glaze | Dimpled | Shivering | Peeling | Majolica:

blackening | Blurring | Glaze crawls over underglaze | Frizzled color | Spit out | Unplanned

color changes | Underfired decals | Overfired decals | Black spots in porcelain and bone

china | Bad adhesion of slip resists | Inability to remove resists post-firing | Tannin

marks | Cracking | Cratering | Surface cleaning problems | Glaze run |

Items adhering to the kiln shelf

All the common problems, why they happen, and how to fix them

TROUBLESHOOTING FOR POTTERS

All the common problems, why they happen, and how to fix them

TROUBLESHOOTING FOR POTTERS

TROUBLESH

OOTING FOR POTTERS

Jacqui Atkin is a professional studio ceramicist who also teaches pottery and occupational therapy in many colleges throughout the U.K. She is the author of several books, including Handbuilt Pottery Techniques Revealed and Pottery Basics, both published in North America by Barron’s.

JACQUI ATKIN

ATK

IN

Handy diagnostic charts at the beginning of the book

provide a super-quick reference for problems

and solutions!

CrazingIn Raku, thermal shock is essential for crazing effects

Saving a surfaceUse metal leaf to add a precious touch Raku resist slips

Why use food coloring to stain the slip?

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Clay bodies, produced by mixing various materials for specific qualities including color and firing ability.

u A very dark gray stoneware clay with flecks of iron dispersed throughout.

ANN VAN HOEYThese finely made slab forms have been cut and folded like origami while being supported in plaster molds during construction and drying.

u The high iron content gives red stoneware clay its color.

u Porcelain is a very white clay.

u A standard, buff-colored stoneware clay.

u White earthenware is gray before it is fired.

u Red earthenware.

Clay bodies—what are they?

Few clays can be used directly from the ground; other additives have to be introduced to give particular attributes—for example, to aid plasticity, lower or raise firing temperature, or change color.

When clays and other materials are combined in this way, the resulting product is referred to as a clay body. Most commercially available clays are prepared by blending different raw materials. Highly plastic ball clay forms the basis of most prepared bodies (along with other ingredients such as bentonite) to provide handling strength. In addition, other minerals such as feldspar, alumina, or silica or nonplastic materials such as china clay, china stone, or whiting can be included to give a body the characteristics required by the potter.

In general, the greater the amount of clay in a clay body, the greater the green strength (unfired strength)—but also, the greater the wet-to-dry shrinkage.

Ball clays are more plastic than fireclays (with some exceptions) and very much more so than china clays, so replacing the first with the latter will greatly reduce green strength.

The addition of grog reduces green strength but also reduces shrinkage and improves thermal resistance, making a body less likely to crack in firing.

Clay bodies are generally classified in three main types: earthenware, stoneware, and porcelain. Within each category there are numerous variations to choose from.

EARTHENWARE CLAYS

Earthenware clays are generally fired within the range of 1922–2102ºF (1050–1150ºC). However, it should be noted that there are some broad-spectrum clays available that are classed as earthenware or stoneware because they will fire up to stoneware temperatures, making them very versatile bodies.

Earthenware is characterized by its porosity when fired and can be any color from the familiar terracotta red through white to buff.

White-burning earthenware bodies have low green strength because they are made up from other materials—china clay and ball clay, plus up to 50 percent non-clay ingredients such as feldspar, Cornish stone, or flint. Talc is another constituent that is widely added to low-firing, white-burning bodies; to prevent moisture expansion, it is added in large amounts to tile bodies. The advantage of these bodies is their low wet-to-dry shrinkage.

Red earthenware clays are generally made up from blended red marls. They may include some ball clay or fireclay but otherwise no “filler,” making their green strength good but wet-to-dry shrinkage high. Sand or grog can be added to compensate for this; to counteract the problem in redware casting slips, 20 percent fine quartz sand is included as a filler.

STONEWARE CLAYS

Stoneware clays generally fire within the range of 2192–2372ºF (1200–1300ºC) and are characterized by the fact that they become vitreous when fired.

They are made from fireclays or ball clays, or combinations of both with little or no filler, although grog or sand is often added to reduce high shrinkage rates in bodies like these that are made purely from clay. This unfortunately has the effect of reducing the green strength of stoneware bodies.

In their raw state, most stoneware clay bodies are various shades of gray in color. Firing from gray to warm buff or white, the final color is also affected by the type of firing the wares have gone through—oxidized or reduction.

PORCELAIN BODIES

Porcelain bodies fire in the range of 2228–2462ºF (1220–1350ºC) and are characterized by being white, vitreous, and opaque or translucent when fired. Known for being difficult to handle because of their critical moisture range, porcelains can quickly move from being too soft to too dry.

Generally made up from china clay, feldspar, and quartz, porcelains do not contain ball clays because they destroy translucency. Bentonite or organic plasticizers can be added to improve workability (especially for throwing bodies), but they have very low green strength and wet-to-dry shrinkage.

Other white-firing bodies include bone china—a type of soft-paste porcelain. It is a vitreous body known for its whiteness and translucency and used extensively in the tableware industry. It is generally made up from about 50 percent calcined bone ash with china stone and china clay. It is a particularly “unplastic” body, rarely worked by hand and most commonly slip cast. It differs greatly from other bodies in that it has a short firing range: as soon as it reaches its eutectic temperature (the lowest melting point of two or more constituents), the body becomes chemically fluid really quickly, which can cause the form to deform—so warpage is very common and there is a high loss rate.

Standard firing temperatures also differ in that bisque is fired to 2282ºF (1250ºC) with a 1½-hour soak, taking the body to vitrification, but glazed only to 1976ºF (1080ºC).

GAIL NICHOLSThis vessel showcases soda vapor glazing. The work is gas-fired to Orton cone 11 and the soda is introduced at cone 9–10.

JO DAVIESThese irregular forms have a light-hearted sensuality that lacks the formal rigidity of many geometric shapes. They are wheel-thrown in porcelain, modified while wet and finished with an opaque crackle glaze.

Job No: CPJ0214-23/Janet3rd Proof Title: FIPO_Troubleshooting For Potters : 30120

Job No: CPJ0214-10/peihua2nd Proof Title: FIPO_Troubleshooting For Potters : 30120