Contemporary Raku E-Book

Stephen Murfitt

• Herausgeber: The Crowood Press
• Kategorie: Lebensstil
• Sprache: Englisch

Seitenzahl: 187

Veröffentlichungsjahr: 2022

Beschreibung

Contemporary Raku is a complete guide to this exciting, dramatic and beautiful art form. It explains the making, glazing and firing methods employed for producing Raku-ware, and features contributions and insights from leading makers. Recognizing the deeper values of the practice, the book also considers the influences and sources of inspiration behind the work of these makers. It introduces the necessary tools and equipment, and advises on essential health and safety measures. It explains how to make vessels and forms with step-by-step photo sequences. Recipes for clay bodies and glazes for the beginner and the more experienced maker are included. Details are given on the Raku-firing process and the range of kilns used. Finally, it explores the practice of 'Naked Raku'. With over 300 illustrations, it is a stunning and detailed account to this magical process.

Leseprobe

CONTEMPORARY

RAKU

First published in 2022 byThe Crowood Press LtdRamsbury, MarlboroughWiltshire SN8 2HR

[email protected]

This e-book first published in 2022

© Stephen Murfitt 2022

All rights reserved. This e-book is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorised distribution or use of this text may be a direct infringement of the author’s and publisher’s rights, and those responsible may be liable in law accordingly.

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

ISBN 978 1 78500 994 5

Cover design: Sergey TsvetkovCover photographs: Terry Beard

Disclaimer

The author and publisher accept no liability for any injury incurred while following the processes in this book. Please ensure that masks, safety goggles and protective gloves are worn when handling dangerous materials. Potential health and safety hazards are indicated throughout the book with an asterisk.

CONTENTS

CHAPTER 1 Introduction

CHAPTER 2 Influences and Inspiration

CHAPTER 3 Making for Raku

CHAPTER 4 Glazes for Raku

CHAPTER 5 Naked Raku and Unglazed Ware

CHAPTER 6 Raku Firing

CHAPTER 7 Health and Safety

Acknowledgements

Suppliers’ Websites

Contributing Makers

Bibliography

Index

CHAPTER 1

INTRODUCTION

R aku is a Japanese word that has been freely interpreted in the West as ‘enjoyment’.

The ‘enjoyment’ is generated from the ‘full-on’ involvement and total engagement with an exploration of ideas interlocked with a magical process! It is a constant search for an elusive unknown perfect outcome. The famous potter Hans Coper once compared his work to that of a ‘demented piano tuner, trying to approximate a phantom pitch’. Many contemporary makers are engaged in a way of working which could be defined as ‘Raku’, a fusion of ideas and process that continues to develop and evolve. In this book, the concept and practice of Raku is revealed through insights provided by some leading practitioners, informed by the first-hand experience that is constantly increasing their knowledge.

Stephen Murfitt, tall textured vessels; height 60cm.

Pottery is as tactile as it is visual and should be seen and experienced in the round. Manipulating clay and making is an extremely tactile experience. As the forms slowly develop, intuitive decisions are made. A change of direction here, a seam added there, more scraping and refining required. Developments that take place during the making process are influenced and informed by ideas that have been developed from experiences absorbed and observations made over many years.

Visual connections are noted, memories of museum visits and ancient pots revisited. Sketchbooks are referred to, and even older and undeveloped ideas remembered. The anticipation of the firing to come builds as recipes are adjusted and pieces are glazed, with some new combinations of colour to be explored.

The first piece is gently placed in the kiln and as the temperature slowly rises, the excitement and expectations increase. The glaze has matured and the vessel is carefully removed from the kiln with metal tongs and placed onto a pre-prepared bed of sawdust and wood shavings. Flames and smoke erupt as more shavings are added and the lid is put on the bin. The hours slip slowly by, the lid is removed, with a combination of expectations, doubts, anxiety and enjoyment, the form (still very hot) is slowly revealed. That fundamental desire to create, the total involvement with the drama of the firing process and the hopeful anticipation for the potential of the outcome, are all part of the Raku experience.

The earliest Raku was produced in Japan around 500 years ago, and has been greatly developed since those early beginnings to become the exciting and constantly evolving practice used by many leading makers of ceramics today.

As with most creative processes, there is never a right or wrong way to do things. There will only be ways which work for the many individual and inventive makers currently involved with a particular process. Experimentation is the key to progress in all creative fields, and for me personally, each firing is an experiment! The results from the kiln will often indicate another focus for the next firing. This will usually involve further developments being made to forms and surfaces.

THE ORIGINS OF RAKU

Raku has its origins in the sixteenth-century tea ceremonies of Japan. The greatest of the tea masters was Seno-Riyku (1522–91). He established the concept of ‘Wabi’, which translates as ‘austerity’ or ‘simplicity’.

Rikyu commissioned Chōjirō to make Raku ware which he felt best represented the idea of ‘Wabi’ and was most fitting for tea ceremony use. Usually these were ‘pinched and hand-made simple bowl forms’, often with a subdued glaze of shades of grey through to black.

Japanese Raku tea bowls attributed to Raku Sonyu and Raku Chongu; 11.4cm and 12.4cm diameter. Toshiba Gallery of Japanese Art, V&A. (PHOTO: CERAMIC REVIEW)

Sebastian Blackie was my tutor at Farnham and later succeeded Henry Hammond as Head of the Ceramics Department. Sebastian went on to become a Professor of Ceramics for the MA course at Derby College. Sebastian here provides an insight into the development of Oribe ware and how this relates to the contemporary approach to Raku.

Since 1996, Gifu Prefecture in Japan have offered a ceramic award. It is named after the warrior and tea master Futura Oribe who inspired a new and distinctive style of ceramics. The award is for innovation, its purpose to spread ‘Oribe-ism’, its ‘spirit’ rather than the shapes, glazes and decoration that emerged in an explosion of creativity over a few short years in the late sixteenth century before settling into a rigid set of forms known as Oribe ware over the next 400 years. The ‘spirit’ of Oribe seems more about spontaneity, creativity and play than technique or style.

I do not consider myself as making Raku but I accept that my potting might, in a similar way to ‘Oribe-ism’ be in the ‘spirit’ of Raku, something that involves performance as well as product, an approach that plays with process and sees the firing as making a significant creative contribution to the production of the work. Raku is individualistic and clearly speaks of values far from that of industry or contemporary consumer culture. It is about recognizing and accepting what is given rather than imposing. It might then be best understood as a philosophical idea in material form embracing any process that elucidates similar ideas.

It was Bernard Leach who introduced the concept of Raku to the West. His famous Potter’s Book contains a description of a garden party in Tokyo in 1911. This included a tea ceremony and participation in a Raku firing, which was Bernard’s first pottery experience.

Raku soon became known in the West as a process in which pots are rapidly fired, and removed from the kiln when glowing red-hot. A more recent Western development was to place the glowing pot into a metal bin or pit which contained combustible materials, creating many colours, textures and metallic lustres. This became known as post-firing reduction and involved the restriction of oxygen inside a reduction chamber, usually a metal bin. This often created some striking and dramatic surface effects.

Raku has evolved into the exciting and challenging process now being explored by contemporary potters using many varied and individual approaches.

PAUL SOLDNER

The Raku process was explored and developed by the American artist and potter Paul Soldner during the 1960s. His strong sculptural pieces (often thrown and altered) were decorated using engobes and metal oxides, and expressed Soldner’s intuitive feeling for the affinity of form and decoration. It was Soldner’s approach to the Raku process that made a huge impact on the work of potters in the West. Here Sebastian Blackie gives an account of his first-hand experience of Paul Soldner and his approach to Raku.

CHAPTER 2

INFLUENCES AND INSPIRATION

T he makers featured in this book each have many years of experience in developing their very individual approaches to the art of Raku. The knowledge gained and awareness developed over those years will help to inform each batch of new work. As the work is created and developed, awareness and experience increase.

Detail of textured turquoise vessel by Stephen Murfitt.

CHAPTER 3

MAKING FOR RAKU

A s I begin to wedge and knead the clay in preparation for the next batch of pots, those familiar feelings of anticipation and excitement for the potential of making begin again! These are feelings that I associate with each stage of the Raku process. From the preparation of the clay through to the making, glazing and firing of each piece, each of these activities forms a vital element of the Raku experience.

Scraping a form with a hacksaw blade.

CHAPTER 4

GLAZES FOR RAKU

T here are infinite ways to develop and enhance the surfaces of ceramics, and Raku presents a unique challenge. With Raku wares the focus will be mainly on the aesthetic qualities involved rather than any practical considerations. Exceptions to this will occur when the firing temperatures reach vitrification levels that will decrease the porosity of the clay body.

Detail of textured turquoise vessel.

Over many years I have developed a range of glazes that integrate with the forms, enhancing any surface textures without obliterating them. Through the oxidation and post-firing reduction process, these glazes have the potential for creating a unique and individual identity for each vessel and form.

As with all the processes involved with the making and firing of ceramics, experimentation is the key to development and progress. The creation of all ceramics and particularly Raku is subject to so many variables: the nature of the clay body used, type of kiln and fuel used for firing, temperatures reached and post-firing methods used. As individual potters, we will each develop our own methods and exploit our materials to suit the personal and idiosyncratic ways we work.

A range of Raku glaze test tiles.

Commercially produced ready-mixed glazes are available from pottery suppliers and could be a good way to start. However, I have always preferred to mix and develop my own glazes with the aim of creating a unique and individual quality in the work.

COLOUR AND GLAZES

The clay body will have a significant influence on any glazes used. A white or light clay body will exploit and emphasize the colour potential of the glaze. A darker clay body will facilitate some contrasting variations with the glaze, especially in reduction.

The clay body can also be coated with coloured slips, which could be brushed on effectively as well as dipped and poured over the form. Glaze stains and coloured pigments, such as metal oxides like copper, iron and manganese, can be painted on to the body before glazing or over the glaze before firing.

Potters have mixed these coloured pigments and oxides into the clay body, achieving some unglazed very rich and varied surfaces. Glazes could also be applied over stained and coloured clay bodies to encourage some integrated and exciting results.

Mixing Glazes for Raku

Any glaze that will remain on the surface of the pot during the firing process can be considered a Raku glaze. With experience and experimentation glazes can be adjusted to suit the requirements of individual potters. The glazes found to be most suitable for Raku are those that have a melting point within the low earthenware range up to 1060°C.

What is a Glaze Made of?

A glaze will consist of three key elements: silica, alumina and a flux. Silica forms the glass and alumina provides some body and stability, helping to create an effective surface. The flux helps to control the maturation point of the glaze. The combination of these essential elements with various amounts of other materials can create an infinite number of glaze effects. This will also have a significant influence on the temperature at which the glaze needs to be fired to reach its melting point. The following is a list of materials that I have used for the formulation and development of my own Raku glazes.

GLAZE MATERIALS

Alkaline frit consists of potassium, silica and sodium. Alkaline frits facilitate the formation of crackle in the glaze.

Alumina will increase the viscosity of a glaze and act as a stabilizer.

Ball clay contains high levels of alumina and silica, assisting with the suspension of the mix as well as providing adhesion to the surface before firing.

Barium carbonate will assist the development of matt and semi-matt surfaces.

Bentonite in very small quantities added to the glaze will assist with suspension of particles of glaze powder in the solution.

Borax frit provides a powerful flux within the usual earthenware and Raku temperature range.

China clay contains alumina and silica. It can be used to make a shiny glaze matt. It can also be used to raise the maturation point of a glaze.

Colemanite will provide a strong flux within the earthenware and Raku temperature range. It will also encourage the intensification of colours produced by the oxides in a glaze.

Feldspar provides fluxes as well as alumina and silica in a glaze.

Flint provides extra silica and is often used to balance the silica amount when adjustments are necessary to improve the glaze fit.

Lead bisilicate and lead sesquisilicate also act as powerful fluxes. Lead glazes encourage rich colours when used with colouring oxides. Glazes containing lead should not be used on any ceramics that could come into contact with any food or drink.*

Whiting small quantities will act as a flux and larger amounts will assist in producing a matt surface.

Zinc oxide can be used as a secondary flux in quantities up to 5 per cent. Large amounts will encourage the development of a frosty, matt surface. It is also a useful opacifier.

Some of the basic materials used for mixing glazes.

The Oxide Colourants

Chrome oxide promotes a wide range of greens dependant on the amount added to the glaze.

Cobalt oxide is a very strong colouring oxide. It will produce blues in reduction and oxidation up to 1 per cent. Cobalt carbonate is a similar but milder colourant.

Copper carbonate is a more refined version and will provide similar though milder results.

Copper oxide produces a range of greens in oxidation. In alkaline glazes it gives turquoise blues. In reduction copper reds and lustred surfaces can be produced.

Iron oxide is known as ferrous oxide, ferric oxide or Crocus Martis. It is a most popular colourant in ceramics and will give yellows, browns, greys and blacks. The oxide will respond to different glaze recipes and kiln atmospheres. In the Raku post-firing process, iron oxide can contribute to a dark, metallic sheen formed on the glazed surface.

Manganese dioxide will give blacks, purples and browns dependant on the recipe used. In reduction it can contribute to metallic sheens produced on the surface.

Nickel oxide generally provides greenish and brownish greys. It has proved to be a helpful modifier for the brighter colours like cobalt and copper oxides. It can also produce greens and greys in combination with amounts of chromium oxide.

Rutile is a natural titanium dioxide with up to 15 per cent iron oxide, which gives it a yellow colour. The yellow colour is retained when rutile is used in glazes and some bright oranges, yellows and creams can result from association with tin oxide and red iron oxide. Yellow-greens can be produced when rutile is used in association with cobalt and copper oxides.

Tin oxide amounts from 5 to 10 per cent will produce a soft blue-white opacity. It does not melt completely in the glaze, so it fills the glaze with white particles, making it opaque. If a heavy post-firing reduction takes place, a strong iridescence can be produced on the surface whilst retaining the white glaze underneath.

Vanadium and uranium oxides* will assist with the production of yellows.

A selection of colouring oxides.

An effective recipe for a Raku base glaze, with the addition of some oxide colourants to be heavily reduced and demonstrate that iridescent outcome:

Ingredient

Percentage

Lead bisilicate

86%

Ball clay

8%

Tin oxide

6%

Keeping in mind that all Raku glazes will be subjected to so many variables; kiln type, level of reduction, combustible material used for reduction, and even the weather conditions on the day, for example rain, wind or storm would all affect the amount of smoke produced.

*Health and Safety: Important Precautions

Many ceramic materials are toxic and must be handled with extreme care. Take precautions, especially when preparing dry materials, to prevent the inhalation of dust particles. Wearing and using the correct equipment will protect from hazardous substances.

Ask for health and safety data sheets when purchasing ceramic materials. These will enable you to assess risk and apply any required measures.

MIXING A GLAZE: TOOLS AND EQUIPMENT

Most of the items used for glazing can be obtained for a relatively small outlay. These include plastic jugs, bowls and lidded buckets. Screw-top jars, ideal for storing small amounts of materials such as oxides and glaze stains can be obtained by recycling coffee jars, jam pots and all manner of containers with screw-top lids.

If it is intended to mix large quantities of glaze, an electric mixer is a very useful piece of equipment. It also facilitates the breaking up of thick and solid accumulations of glaze materials that settle at the bottom of glaze bins.

Much more important than expensive equipment is an understanding of the risks involved with mixing and applying glazes, and a constant adherence to safe practice.

You will need:

• Accurate scales, for large and small quantities of materials.

• A range of sieves with various mesh sizes. Typical mesh sizes are 60, 80, 100 and 120, the highest being the finest mesh. It is possible to go up to a 200 mesh but a 60–80 size is suitable for general purposes. For glazes that will be sprayed, a finer size (100–120) is necessary in order for the mixture to pass through the small nozzle of a spray gun.

• A large, stiff brush for pushing the glaze materials through the sieve. An ordinary domestic washing-up brush is fine for this purpose.

• Buckets or containers with tight-fitting lids for safe, airtight storage of materials.

• Some slats suitable for supporting a sieve over a bucket.

• A plastic jug for measuring out the required amount of water to be added.

Mixing the Glaze

It is essential to follow the advice given in the health and safety section of this book. All dry powder ceramic materials should be mixed into water as soon as possible. Ceramic dust is a potential health hazard. It is most important to develop a system for storing all dry glaze materials in clearly labelled containers with airtight lids.

Weigh out the dry ingredients and gently add them to a large bowl with more water than is eventually required. This will result in a thin mixture, which reduces the dust hazard and helps to inhibit lumps from forming.

Mix this ‘slop’ thoroughly, either by hand (suitably protected with rubber gloves) or using an electric mixer to break up any remaining lumps of material.

Put the mixture at least once through a sieve using a large, stiff brush. If the mixture is particularly lumpy, use a 60 mesh to begin with. Then progress on to a 100 mesh. This process will result in a homogenous, evenly mixed glaze.

The chosen method of application will influence the required thickness of the glaze. As a general guide, a glaze intended for dipping should have the consistency of single cream. A glaze for spraying should be put through a 120-mesh sieve and will be of a slightly thinner consistency. Glaze thickness can be tested by dipping a finger or a piece of biscuit-fired pot (or test tile) into the thoroughly stirred mixture. If the glaze runs off, it is too thin. Allow the glaze to settle with the ingredients sinking to the bottom. This can take from one to twenty-four hours, depending on the materials in the glaze. Glazes high in clay content are slower to settle, whereas non-plastic ingredients, such as frits, settle quickly.

Some equipment and materials for mixing glazes.

The dry materials are weighed out and carefully placed in a suitable bowl.

Enough water is added to submerge the dry materials.

Mixing the raw materials thoroughly by hand.

Putting the glaze mixture through an 80-mesh sieve.

Using a large brush to push the residue glaze materials through the sieve.

Excess water can then be removed from the top of the glaze with some careful ladling. Always stir the glaze thoroughly before use to ensure an even mix of all the ingredients. Glazes that contain frits will require constant stirring, which helps to prevent them from settling to the bottom of the bucket.

Commercially produced glazes can be purchased from most pottery suppliers. They come in powder or liquid (ready mixed) form. A wide range of glazes and glaze colours come, ready to paint on, in small screw-top jars.

METHODS OF APPLICATION

The key to developing personal and innovative ways of working with glaze is experimentation. An infinite variety of surfaces is possible, and there are many methods for achieving them. Described here are some of the most frequently used techniques.

Resists

Before glazing, resists such as wax, latex and masking tape can be applied to create areas to be left unglazed. After glazing, tape can be peeled away, while resists such as wax and latex will burn away in the firing, enabling black carbonized areas on the body to be revealed after post-firing reduction.

Peeling away the masking tape resist.

Raku vessel after firing showing the effects of wax and masking tape resists.

Detail of resist effects after reduction.

Pouring

Glaze can be poured over small pots held over a bowl or bucket to catch the excess liquid. Larger forms can be supported on wooden slats over a suitable container. The glaze is then poured evenly over the form. Dramatic effects can be created by overlapping poured glazes, by using the same glaze or a combination of glazes.

The glaze is carefully poured over a pot using a jug.

A pot after firing, showing the effects of poured and overlapping glaze.

This Raku form had one glaze poured over another to create a dramatic effect.

Swilling the glaze around the interior of a large bowl.

It can be seen that the swilling action has created overlaps with different thicknesses, which can create dynamic effects.

The large bowl after firing, showing the effects of the glazed interior.

The interiors of large bowl forms can be glazed effectively by pouring in the glaze and then swilling it around, and then pouring the excess back into the glaze bucket.

Dipping