Stoneware Glazes, A Systematic Approach by Ian
Bootstrap Press (Australia)
Seeing some stunning glaze tests mounted for display by mature students while I was visiting Brisbane to give a lecture in 1981, first brought the name Ian Currie to my attention. Later that year an article by him on his methods in Pottery in Australia stimulated me to try his system. I quickly found some off-beat glazes which I use in oxidation. Last year I discovered he had written a book which appeared first in Australia in 1983 and is now available in the United Kingdom. The book is a course on stoneware glazes which the author, Ian Currie, states in his introduction, began back in 1972 when he investigated the Japanese approach to the subject. This lead to courses and booklets which Ian eventually brought together to form the present book.
The first part explains the system of experiment and the rationale behind it, leading into preparations for the type of testing that will be done and advising on the raw materials to be used. There are sections on volumetric blending using a ml. syringe and the type of test tiles to be made, and line blending of rock, clay and ash. It is all meticulous ly laid out with drawings and diagrams.
The core of the method is a series of investigative experiments in which four corner recipes are given which when blended together yield a grid of thirty five tests. These experiments are carefully chosen to give a spectrum of the main fluxes in stoneware glazes kept constant at a particular molecular part in a base glaze where only the alumina and silica are varied. The main experiments have this flux in a dominant proportion but there are intermediate sets where it has a lower M.P value. The results can then be attributed to the qualities of the flux and the varying alumina and silica, only. There are fifteen of these experiments or sets. Each one has a section with a commentary on the flux and a set of grid diagrams with the tests located which show glazes of matt, shiny, crystalline, semi-matt opaque, sugariness and so on.
Although the Seger Formula system is used to
locate the test points, if the word Seger terrifies you do not be
put off. All the thinking, planning and foresight have been
done by the author - no previous knowledge is necessary.
Similarly if you are fainthearted and do not want to conduct an
entire experiment, or have no need to, you can choose any one of
the thirty-five and make a spot test using the results
charts. Each section has the materials recipe for each of
the thirty-five tests as well as the oxide percentage analysis
and the Seger formula for that point. There are over 500
recipes in this part of the book to choose from. What Ian
Currie has done is to cut a wide path through the jungle to lead
us to the Temple of Understanding and the Right Glaze.
This is Part 1 of the book. There is a substantial Part 2, which deals with specific glazes. Among othere there are sections on crystalline, matt, chun, white ware, high iron, celadon, kuan, shino and copper. As well there are sections on woodfiring effects and rock glazes. These contain a cornucopia of information culled from acknowledged sources and his own experience and research. There are many more recipes in this part and more experiments and suggestions to work on with the recipes supplied.
Ian Currie has produced a winner. He is to be congratulated on this work which breaks much new ground and which will be of value to beginner, student, teacher and experienced potter alike. It must surely become one of the standard works on the subject.
Stoneware Glazes, A Systematic Approach
by Ian Currie
Published by Bootstrap Press
While this book has been specifically written for the artist ceramist, it is so comprehensive that it deserves the appreciation of a far wider audience. It is an extremely practical guide which was initially written as a correspondence course for the Australian Flying Arts School. As such, beginners can readily understand the clear and concise text; lecturers are provided with a teaching framework unifying theory and practice; and experienced potters have a valuable reference book. Not surprisingly, the first edition (1985) was so well received that it has now become a standard text in most Australian ceramic art technical college courses, and a second printing was needed.
Ceramic technologists may be pleasantly surprised to find numerous pages of charts and tables. While this data may initailly appear quite complex, and thus daunting, it becomes refreshingly comprehensible when one understands the logic behind the experimental technique. This book thus forms an important link between ceramic art and technology.
The book is written in two parts. The
first part is essentially a systematic examination of base
glazes, i.e. basic glazes to which colourants or opacifiers may
later be added. The introduction to the rationale behind
the experimental procedure is particularly lucid. Currie
correctly maintains that glaze properties such as mattness,
gloss, transparency, opacity, opalescence, glaze fit, many colour
responses, etc. can usually be simply explained by reference to
the base glaze. After discussing the effects of varying the
silica and alumina contents, he introduces eight sets of base
glazes (principally based on K2O and CaO, although some contain
MgO, BaO, ZnO or BaO and Li2O). Thus from an infinite
number of possible variations, Currie has selected those ranges
of variables most suitable for the stoneware potter, and has
varied the glaze components and the firing conditions in such a
way that one can isolate an individual variable and determine the
effect it has on a glaze. Extensive data sheets are
provided for each set of glazes, giving Seger formula, % oxide
weight, and one or more typical recipes for each glaze, together
with some results charts. Obviously this framework can be
extended to the study of other systems, and Currie provides
guidance on designing one's own experiments. In this
regard, the chapter on phase equilibria diagrams and eutectics,
and also that on glaze calculations, would undoubtedly be of
benefit to the novice.
Part 2 deals with specific glazes including crystalline, matt, opaque, Chun-blue, white, high iron, celadon, Kuan, Shino, copper, rock glazes and natural glazes from woodfiring, and refers back to Part 1, so that these glazes may be better understood in terms of the glazes on which they are based. While the individual chapters on these glazes are again a combination of theory and practice, I was impressed by their diversity and the fact that given a few details, the practicing potter may start to develop his own approach towards achieving the desired end effect, although the supportive framework is still there to provide further guidance. The wisdom acquired over the centuries has been masterfully condensed and should the summary of the factors affecting the development of the glazes prove insufficient, suitable references for further reading are provided. These chapters contain several recipes ( with suggested alternative raw materials where whose specified are unlikely to be available), developmental exercises and a treasury of practical information. This book will undoubtedly benefit anyone who wants a greater insight into glazes.
Richard Bowman, CSIRO Division of Building Research
Stoneware Glazes: A Systematic Approach by Ian Currie (Bootstrap Press)
Only occasionally does a book come along that is instantly recognisable or a classic in its field. As a teacher I have had considerable difficulty suggesting a book as a text for courses on glaze as, until the publication of this book, not one book was available that covered the field adequately. It could be said that Stoneware Glazes fills the need for a comprehensive glaze technology text and that it represents the state of current knowledge about its subject matter. It is complete, thoroughly researched and it offers the potter a systematic approach to the theoretical and practical aspects of glazes.
The book is a totally revised, updated and enlarged version of the notes that accompanied the highly successful Correspondence Course in Stoneware Glazes that Ian prepared for the Flying Art School run by the Brisbane College of Advanced Education. I first came into contact with this course about five years ago and it was a revelation to me that by following Ian's concept of 'base glazes' I was able to discover more about glazes in one year than I had in the previous 10 years or was likely to in the next 10 years of an essentially haphazard approach. Ian's simple concept of looking at glazes in a graphic formation with one axis for increasing alumina and one axis for increasing silica, whilst holding the fluxes constant, had appeared before, but no one has taken it to its conclusions, i.e. of examining various dominant fluxes and comparing these with each other.
It is Ian's genius and hard work in developing the approach, selecting the appropriate tests and finally putting the whole lot into a readable and understandable form that brings the reader to the right conclusions. Stoneware Glazes in not about theory - although all the theory is presented, it is a practical method. Ian has started with the premise that the reader has no previous knowledge of glazes, but has a lot of enthusiasm and inquisitiveness. In the early chapters he treats basic chemistry as he did in the correspondence course, clearly and concisely, leading the reader into understanding all the necessary concepts and the reader is soon capable of doing molecular formulae as if they came naturally.
The first part of the book is devoded to building knowledge to the point of doing the base glaze tests, which are the core of the course. Alumina and silica in glazes are discussed at length, then the lime alkali, magnesium, zinc and barium tests are described. The point is for the reader to do these tests, but even without doing them the result sheets, graphs, computer print-outs and notes are enough to justify the book's small purchase price.
Part II of the book takes a more detailed look at various glazes including crystalline, matt, opaque, chun-blue, white, high iron, celadon, kuan, shino, copper-red, natural (Bizen) and rock glazes. These all get a complete chapter covering in detail their theory, testing procedure and recipes given. All these glazes are thoroughly and authoritatively tested.
Stoneware Glazes is ... packed with the best information available on glazes today. All glazes are now available to all, and it will be hard work and aesthetic sensitivity that will make good pots. I can give this book no higher praise than to say that one copy sits beside Leach, Cardew and McMeekin on my book shelves and I carry another with me to all my glaze classes.