C for Studio Pottery: a Systematised Development of Raw Glaze Theory and Practice for Once Fired, Midfire Purposes Ivan Oscar Englund University of Wollongong
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University of Wollongong Research Online University of Wollongong Thesis Collection University of Wollongong Thesis Collections 1995 Glazes between 1100[degrees]C and 1200[degrees]C for studio pottery: a systematised development of raw glaze theory and practice for once fired, midfire purposes Ivan Oscar Englund University of Wollongong Recommended Citation Englund, Ivan Oscar, Glazes between 1100[degrees]C and 1200[degrees]C for studio pottery: a systematised development of raw glaze theory and practice for once fired, midfire purposes, Doctor of Philosophy thesis, Faculty of Creative Arts, University of Wollongong, 1995. http://ro.uow.edu.au/theses/1753 Research Online is the open access institutional repository for the University of Wollongong. For further information contact Manager Repository Services: [email protected]. GLAZES BETWEEN 1100°C AND 1200°C FOR STUDIO POTTERY A Systematised Development of Raw Glaze Theory and Practice for Once Fired, Midfire Purposes A written submission in partial fulfilment of the requirements for the award of the degree I UNIVERSITY Of | WOLLONGONG DOCTOR OF CREATIVE ARTS from UNIVERSITY OF WOLLONGONG by IVAN OSCAR ENGLUND FSTC ASTC Faculty of Creative Arts 1995 CERTIFICATION I certify that this work has not been submitted for a degree to any other university or institution and, to the best of my knowledge and belief, contains no material previously published or written by any other person, except where due reference has been made in the text. Ivan Oscar Englund 21 June 1995 GLAZES BETWEEN 1100°C AND 1200°C FOR STUDIO POTTERY A Systematised Development of Raw Glaze Theory and Practice For Once Fired, Midfire Purposes ABSTRACT This research investigates "middle fire" ceramic glazes in the firing temperatures between 1100 and 1200 degrees centigrade (Seger cones 1 to 6). It addresses an area of firing temperatures that has been largely neglected over the centuries, in contrast to both earthenware and stoneware about which there is a vast amount of information available. The research shows, however, that there is evidence of a current growth of interest worldwide in midfiring for reasons of economy and ecology. The author's long invovement in pottery extending over forty years positions him well to develop glazes in this study which compare favourably with those in other temperature ranges. Of added significance and originality the middle fire glazes have been developed for "once firing" or "raw glazing" where glaze is applied to the damp pot thereby eliminating the biscuit fire. Researching the literature of ceramic studio work done both in Australia and overseas has yielded no reference to this method of glaze application at the middle fire temperatures. The combination of middle firing and raw glaze application is worthy of consideration because each part of the process saves on fuel consumption. There is a saving in costs for the potter and there are benefits to the ecology with less fossil fuels used, less greenhouse gasses created and less contribution to the possible global warming. The dissertation is of necessity a technical paper put into perspective by a brief examination of the history of glazes, as seen from the viewpoint of a potter as opposed to the traditional archaeological viewpoint. Early pottery from the Middle East, China, Japan, Korea and Europe are considered. The links between these Asian and European traditions and Australian ceramics, introduced by Bernard Leach with the publication of his A Potter's Book, are described as the basis of Australian glaze traditions. Recipes for raw glazes firing at Seger cones 1 to 6 are listed together with descriptions of the fired results and Seger formula calculations. Table of Contents 1 Introduction 1 2 The Earliest Pottery - A Brief Historical Survey 3 Western History 5 Eastern History 9 European Lustre Ware 22 European Tin Glaze 24 3 Industrialisation and Studio Pottery 26 The Leach Contribution 28 The Australian Scene 30 4 The Middle Fire Glazes 49 5 Working the Seger Formula 55 6 Bentonite and Once-Fired Glazes 61 Raw Glazes for Reduction and Oxidised Once Fired Purposes 69 8 Bibliography 9 Appendix 1 - Glaze Calculations 10 Appendix 2 - Clay 11 Appendix 3 - The Exhibition ACKNOWLEDGEMENTS Beryl Margaret Anderson Professor Sharon Bell Dennis Chapman Professor Barry Conyngham Annette Diamant Lindsay Duncan Professor Peter Fielding Dr Bert Flugelman Ian Gentle Andrew Hunter Sandra Indlekofer-O'Sullivan Elizabeth Jeneid Daniel Midwinter-Hampton Dr Sue Rowley Dr Peter Shepherd Julia St George The Walcha Telecottage Allan and Leslie Wickham Chapter 1 INTRODUCTION GLAZES BETWEEN 1100°C AND 1200°C FOR STUDIO POTTERY: A Systematic Development of Raw Glaze Theory and Practice for Once Fired, Midfire Purposes This research investigates "middle fire" ceramic glazes in the firing temperatures between 1100 and 1200 degrees centigrade (Seger cones 1 to 6). In my opinion this area of firing temperatures has been largely neglected over the centuries in contrast to both earthenware and stoneware, about which there is vast amount of information available. My research shows, however, that there is evidence of a current growth of interest worldwide in mid-firing for reasons of economy and ecology. Because of my long invovement in pottery extending over forty years I am in a position to authoritatively evolve glazes in this study which will compare favourably with those in other temperature ranges and that will be as attractive to potters as are the more traditional glazes in the low fire earthenware area and in the high temperature field of stoneware. I have therefore extended my earlier work on cone 4 glazes to cover the complete firing range between cones 1 and 6. Of added significance and originality my middle fire glazes have been developed for "once firing" or "raw glazing" where glaze is applied to the damp pot thereby eliminating the biscuit fire. My research into the literature of ceramic studio work done both in Australia and overseas has yielded no reference to this method of glaze application at these middle fire temperatures. I regard the combination of middle firing and raw glaze application as very important, as each part of the process saves on fuel consumption. There is a saving in costs for the potter and there are benefits to the ecology with less fossil fuels used, less greenhouse gases created and less contribution to the possible global wanning. I regard this study to be an important contribution to the expansion of knowledge in the very long history of ceramics. This dissertation is of necessity a technical paper put into perspective by a brief examination of the history of glazes, as seen 2 from the viewpoint of a potter as opposed to the more traditional archaeological viewpoint. The earliest pottery known from the Middle East is examined and contrasted with the Chinese wares from Shang to Ming dynasties, the Japanese and Korean potteries and finally with the European lustre and tin glazed wares. The Australian colonies depended largely on European ceramic technology until the publication of his A Potter's Book by Bernard Leach.1 His writings about his work with Hamada in Japan and his own experience of stoneware in Britain raised the Australian awareness of the importance of the Song wares and the place that high fired wares such as porcelain and stoneware could play in the work of studio potters. The Leach/Hamada tradition was sewn into the post-war Australian art evolution by potters such as Ivan McMeekin, Mollie Douglas, Peter Rushforth and myself. Our collaboration founded the Potters' Society of Australia, a significant influence in disseminating knowledge to Australian potters and fostering the growth of serious studio pottery through discussion groups, lectures and workshops. Each one of our four separate career paths is described. My special involvement in mid-fire raw glazing and my research in developing suitable glazes forms the focus of this dissertation. I have used the Seger formula method of evolving glazes and this is described in detail. I have illustrated its use with an example of a glaze based on a eutectic which melts at 1160 degrees centigrade the formula of which is 1 CaO, .35 AI2O3, 2.48 Si02- I have then tabled calculations to incorporate bentonite as the key variable component for glazes to be applied to the leather hard pots, the so-called once fire or raw glaze method. Recipes for raw glazes firing at Seger cones 1 to 6 are listed together with description of the fired results and the complete Seger fomula calculations for the above glazes are given as tables in Appendix 1. In Appendix 2 some commercial clays suitable for firing at these temperatures are discussed together with some body recipes for potters who wish to make their own and in Appendix 3 are details of my Exhibition at the Bloomfield Galleries, Paddington which showed pots using some of the glazes from this study. Old age hath yet his honour and his toil. Death closes all; but something ere the end, Some work of noble note, may yet be done ... (Tennyson) Bernard Leach. A Potter's Book. Faber and Faber, London, 1940. 3 Chapter 2 THE EARLIEST POTTERY - A BRIEF HISTORICAL SURVEY. In approaching almost any matter relating to pottery and especially that involving research there is an overwhelming sense of the vast history of the subject. Making pottery was one of the earliest crafts, along with basket making, weaving, the making of weapons, undertaken long ago in prehistory. One can speculate with regard to weapons that it seems likely that a stick may have been used for defence or attack and this could logically have evolved into a spear for throwing or jabbing by sharpening it into a point. Perhaps by chance it would have been found that the point could have been improved by hardening in a fire.