But since gb is so plastic, adding more plastic materials to a glaze causes excessive drying shrinkage producing cracks and ultimately crawling. Does anyone know a european substitute for ferrofrit 3124 and gerstley borate. Gillespie borate was developed through a careful formulation process that has resulted in a virtual chemical match to gerstely borate. The calcium borate and sodium calcium borate found in this ore offer a form of borate which is very slowly soluble in water. Gerstley borate refers to the substance extracted from a certain nowdefunct mine, it is not calcium borate, and in fact it does not even have a consistent chemical composition. Issuu is a digital publishing platform that makes it simple to publish magazines, catalogs, newspapers, books, and more online. The introduction notes that many glazes circulating among potters or printed in books are unsatisfactory for several reasons. Gillespie borate is comprised principally of ulexite sodium calcium borate, with small amounts of colemanite calcium borate and other minerals just like. For the past 50 years, gerstley borate has been used by many potters. Gerstley borate is a mineralbased product and no specific hazardous properties have been observed. This base has some troublesome issues which include slurry gelling because of the partially soluble gerstley borate and nepheline syenite, consistency and supply issues relating to gerstley borate, susceptibility to blistering and higher thermal expansion because of the high feldspar content. Arbuckle majolica and lowfire page 3 of 9 majolica handout.
Gerstley borate is not used in industry because of its issues. It begins to melt between 1550f and 1600f and is a clear amber glass by 1750f and ultraclear and glossy by cone 06 ulexite melts better but it is not commonly in use in ceramics. A survey of books and magazine articles reveals numerous formulas requiring gerstley borate in low fire cone 06 1828degreesf and mid range cone 6 2232degreesf glazes. Raw materials are weighed, melted together and ground to produce a powdered glass. Gerstley borate material safety data sheet date of issue. Gerstley borate material safety data sheet date of issue may. If you have ever mixed a raku glaze it is very likely you have used a chemical called gerstley borate.
Gerstley is a natural borate similar to but not interchangeable with colemanite on a 1 to 1 basis. Lithium oxide li2o is the lightest weight, smallest particle size and most powerful of the alkaline fluxes with a strong color response similar to sodium and potassium oxides. The ulexite in gerstley borate melts first, producing an opaque fired glass having the unmelted and still gassing particles of colemanite suspended in it. Gillespie borate is a blended borate mineral for use in glaze formulas replacing gerstley borate on a pound for pound basis. To generate a replacement, a new material was created. Gerstley borate has almost no al 2 o 3, this is a problem because glazes need it and al 2 o 3 is normally sourced from clays, especially kaolin. Its raw colour is white to light gray with dark specks. Burgundy red 6 oxidation 21 whiting 31 custer feldspar 18 silica 8 gerstley borate 9 epk kaolin 9 ferro frit 34 4 talc 5 tin oxide 0. Borates article about borates by the free dictionary. This comprehensive reference is the first to cover industrially important borates, from deposits, through chemistry, mining, processing, and applications. Its like trying to hit a moving target when deciding on what chemical formula to use when developing a substitute. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic. This is a conglomerate mineral made up primarily of colemanite, ulexite and hectorite. Since gb based glazes melt well and are so easy to make, most people have overlooked issues surrounding its use.
Gerstley borate real a sodiumcalcium borate compound used as a low and midrange glaze flux. This glaze contains gerstley borate which is composed of a mixture of the minerals colemanite and ulexite. Gerstley borate is a calcium borate ore containing the mineral ulexite. Feb 25, 20 pa frogskin custer feldspar 22 gerstley borate 22 neph syen 22 silica 26 wollastonite 3 epk 3 titanium diox 2 red iron oxide 3 copper carb 4 bentonite 2 stay safe and healthy.
Some materials are notoriously unstable because as they are mined, the chemical composition will probably change. It sources boron, and melts far better than any other common raw material. Use this as a resource for research on your ceramic surfaces. Sep 29, 20 5 gerstley borate 1999 2 whiting 41 feldsparcuster 12 ball clay number 1 10 red art 4 spodumenegwalia 9 dolomite 7 bone ash 3 talc 2 lithium carbonate 5 silica 100 total additives 2 crocus martis 1 manganese dioxide 1.
Gillespie borate gerstley borate substitute sheffield. Please practice handwashing and social distancing, and check out our resources for adapting to these times. Easily share your publications and get them in front of issuus. Maryadams on thu 25 aug 05 am finding beautiful recipes for cone 56 glazes and cone 10 as well and they call for gerstley borate. A sodiumcalcium borate compound used as a flux in glazes. Browse for more products in the same category as this item. It is used to introduce boric oxide in an insoluble form and as a more stable substitute for colemanite. Gerstley borate official composition page from laguna clay. This material is partially soluble and can flocculate glaze slops. The reference work begins with a listing of the 238 currently known borate minerals, their formulas, and properties. A standard substitute in glazes calling for colemanite.
The result is as follows sio2% al2o3% fe2o3t% mno% mgo% cao%. It can help prevent crazing when used in small amounts, and can act somewhat as an opacifier in larger amounts, giving glazes a milky appearance. Raw materials and ceramic chemicals raw materials and ceramic chemicals available for online ordering raw materials pricing by pound less than 50 lb full bag. David hendley on thu 5 aug 99 contrary to what has been said here on clayart last week, the colemanite of old and todays gerstley borate are far from the same material. Keane ceramics is based at somersby on the scenic central coast.
Materials, recipes and techniques a collection of articles from ceramics monthly edited by anderson turner published by the american ceramic society 600 n. It can be prepared by reacting calcium metal with boric acid. If it wasnt for this unique characteristic of gerstley borate it would have been abandoned when the first series of its faults appeared. We have been established for over 30 years and offer an.
Gerstley borate, experiments for substitution alchemist. Numerous and frequentlyupdated resource results are available from this search. Gillespie borate gerstley borate substitute potclays studio. Gerstley borate are notlisted on any proposition 65 list of carcinogens or reproductive toxicants. It has been a foundation material in low and middle temperature pottery glaze recipes for many years.
Gerstsley borate is an ore which contains a mixture of the minerals colemanite ca2b6o11. Substituting gerstley borate in floating blue youtube. Mar 28, 2009 using digitalfire insight to formulate, fix and adjust ceramic glazes. You might be able to obtain calcium borate by reacting calcium metal with boric acid, but you definitely cannot obtain gerstley borate. Gerstley borate na 2 0 2ca0 5b 2 03 16 h 2 0 a sodium, calcium borate unprocessed ore used as a low temperature flux in clay formulas. Gillespie borate gerstley borate substitute sheffield pottery.
A hydrated form occurs naturally as the minerals colemanite, nobleite and priceite. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Frits are storehouses of oxides which are both stable and predictable. Oclcs webjunction has pulled together information and resources to assist library staff as they consider how to handle coronavirus. Consistency manufactured from high purity refined raw materials, gillespie borate is highly consistent from batch to batch. Gerstley borate is a calcium borate ore containing the mineral ulexite 3cao na2o 5b2o3 16h2o, along with accessory minerals such as bentonite, colemanite, and probertite. Gillespie borate is comprised principally of ulexite sodium calcium borate with small amounts. What we do is make a new and different glaze that uses a similar composition to an. As a control composition for this study 26 percent gerstley borate was used in. A sodiumcalcium borate compound used as a low temperature flux which. The borax chemical formula is also commonly written in a more compact notation as na 2 b 4 o 7 10h 2 o. Calcium borate ca 3 bo 3 2, also called gerstley borate citation needed, is a bluish white crystal with a very defined structure. The tetraborate anion occurs in the mineral borax, or sodium tetraborate octahydrate, with the formula na 2 b 4 o 5 oh 4 8h 2 o.
Gerstley borate is also plastic and suspends and hardens glazes, so it is common to find gb based recipes having no clay content. Using digitalfire insight to formulate, fix and adjust ceramic glazes. It has thus been a staple among potters for many years. Nakai i, appleman d e, chemistry letters, 1981 1981 p. We have rounded these numbers off for inclusion here. Composition information on ingredients substancemixture. I have been using calcium borate for a little over a year or so. A sodiumcalcium borate compound used as a low temperature flux which helps prevent crazing. Gerstley borate is a sodiumcalciumborate compound used in ceramics as a low. Sodium borate can be obtained in high purity and so can be used to make a standard solution in. No common natural material comes anywhere close to melting like gerstley borate gb.
Flux or alumina, you can bet we use it in glaze composition. Name, molweight, na2o, k2o, mgo, cao, zno, al2o3, b2o3, sio2. Some feel this chemical was the spawn of hell due to inconsistency of the supply, how it reacted once mixed, or any number of other reasons. May 01, 2011 for the past 50 years, gerstley borate has been used by many potters.
Gerstley borate is not manufactured with, and does notcontain any class i or class ii ozone depleting substances. The theoretical formula for colemanite yes, it was named for a guy named coleman, in california, in the 19th century is. Gillespie borate is a blended borate mineral for use in glaze formulas replacing gerstley borate on a poundforpound basis. Pa frogskin custer feldspar 22 gerstley borate 22 neph. Gerstley borate is mineralbased product and no specific hazardous properties have been observed. Potters have a lovehate relationship with this material. This website uses cookies to improve your experience while you navigate through the website. Gerstley is a natural borate similar to but not interchangeable with colemanite on. I have several books at home that have those listed but i.
C6 glaze gallery this cone six glaze gallery is tested, photographed and recorded by rat city studios. View uspigmentcorporation165758946784423s profile on facebook. It is a borate source that is virtually identical to the original gerstley borate in terms of physical, mineralogical and chemical composition. Chemical composition of gerstley borate as a service to our customers, we had a qualified, independent agency do an analysis of a sampling of the gerstley borate we have been supplying for years and will continue to supply. A collection of glaze recipes and combinations, in a digital format for the modern potter. Colemanite clay and glaze chemistry ceramic arts daily. Reliable information about the coronavirus covid19 is available from the world health organization current situation, international travel. Gerstley borate supplies b2o3, cao, other fluxes, sio2, and al2o3. Lowfire glaze recipes crusty glaze bb 1 cone 04 30 gerstley borate 50 kaolin 20 cryolite 100 description. The gerstley borate is a substitute for colemanite, but it is much different. Gerstley borate rocky mountain clay clay for teachers.
It is high in sodium and lower in silica than other feldspars and melts around cone 6. The study of the composition and concentration dependence of the lowfrequency light scattering spectra of the borate glasses, 14 has shown that both the type of the alkali metal cation and the concentration of modifier oxide strongly affect the spectral properties of the boson peak intensity and boson peak position see, e. Similar borate salts are considered hazardous under the osha hazard communications. Oxide match virtually identical to gerstley borate, this product requires no adjustment to formula and no extra additives are needed. In france, i am going to the supply store on tuesday to get glaze chemicals for my raku workshop firing next weekend. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are as essential for the working of basic functionalities of the website. Through years of formulation and reformulation, karl miller developed albany slip substitute which is intended to reproduce the physical and performance characteristics of the famed.
I have several books at home that have those listed but i dont have them here. Calcium borate also called gerstley borate, is a bluish white crystal with a very defined. Gerstley borate s wide swings in chemical composition are a factor in finding a direct substitute. Similar borate salts are considered hazardous under the osha hazard communication standard and under the canadian controlled products regulations of the hazardous products act, whmis based on animal chronic toxicity studies. And few people realize how easy it is to replace it to create much easiertouse and less problematic glazes. Calcium borate ca 3 bo 3 2, also called gerstley borate, is a bluish white crystal with a very defined structure. Gerstley borate updategerstley borate is in stock and not going anywhere. Photo is of two test tiles both fired in the same kiln to 1875 degrees f and reduced in the same 10 gallon can with 6 sheets of newspaper 3 torn into strips. Mentioned in many american text books, this is a popular flux in studio glazes. Aug 30, 2017 common midrange sources include sodium feldspars nepheline syeniteactually a feldspathoidis the lowest melting feldspar and so it is often used at midrange. Gillespie borate, which is virtually identical to gerstley borate in terms of physical, mineralogical and chemical composition. Strangely most people have used it without knowing what it really was.