March 2019 identification product name gerstley borate. The theoretical formula for colemanite yes, it was named for a guy named coleman, in california, in the 19th century is. When we try to remake gerstley borate from materials which are commercially readily available on the market, it is necessary to have the chemical formula of gerstley borate. Gerstley borate updategerstley borate is in stock and not going anywhere.
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. 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. Gillespie borate is comprised principally of ulexite sodium calcium borate, with small amounts of colemanite calcium borate and other minerals just like. Mentioned in many american text books, this is a popular flux in studio glazes. The result is as follows sio2% al2o3% fe2o3t% mno% mgo% cao%. Below is a table of the frits we use first column and nearequivalents that may be more readily available in your part of the world. A variety of colemanite, a naturally occurring mineral, specially imported by us from the usa. No part of this book may be reproduced, stored in a retrieval system or transmitted in any.
A sodiumcalcium borate compound used as a low and midrange glaze flux. Gerstley borate s wide swings in chemical composition are a factor in finding a direct substitute. Mar 28, 2009 using digitalfire insight to formulate, fix and adjust ceramic glazes. None, because gerstley borate is not flammable, combustible or explosive. Gerstley borate rasorite 5 firefighting measures general hazard. But since gb is so plastic, adding more plastic materials to a glaze causes excessive drying shrinkage producing cracks and ultimately crawling. Clay composition and crazing clay and glaze chemistry. This material is partially soluble and can flocculate glaze slops. Gerstley borate real a sodiumcalciumborate compound used as a low and midrange glaze flux. Gerstley borate real a sodiumcalciumborate compound used as a low and. Gerstley borate material safety data sheet date of issue may. In the heart of the potteries, we are the uks leading manufacturer of kilns and moulds, as well as a leading supplier of clay, glaze, raw materials and tools.
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. Gillespie borate, which is virtually identical to gerstley borate in terms of physical, mineralogical and chemical composition. The one limitation of borate pressure treated lumber is that it cannot be used for wood in contact with the soil since the moisture in the soil will extract out the water soluble borate within a few years. Its like trying to hit a moving target when deciding on what chemical formula to use when developing a substitute. All other materials were kept at their original percentages and all methods of glaze application and firing were kept consistent. Materials, recipes and techniques a collection of articles from ceramics monthly edited by anderson turner published by the american ceramic society 600 n. Some materials are notoriously unstable because as they are mined, the chemical composition will probably change. Gillespie borate gerstley borate substitute sheffield pottery. Any fire extinguishing media may be used on nearby fires.
Raw materials and ceramic chemicals raw materials and ceramic chemicals available for. 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. Gerstley borate real a sodiumcalcium borate compound used as a low and midrange glaze flux. In our opinion, gerstley borate and colemanite are too variable in composition and of questionable future availability. May 01, 2011 to generate a replacement, a new material was created. Transcript of video 1c comparing calcia sourcing materials 1. Gerstley borate material safety data sheet date of issue. The introduction notes that many glazes circulating among potters or printed in books are unsatisfactory for several reasons. Mastering cone 6 glazes, by john hesselberth and ron roy. Gb is not a mineral, it is an aggregate of minerals which is the book. At middle temperatures gb made it possible to make the variegated and visually appealing surfaces normally associated with cone 910. A standard substitute in glazes calling for colemanite.
It has thus been a staple among potters for many years. Gerstley borate is mineralbased product and no specific hazardous properties have been observed. Gerstley borate is a sodiumcalciumborate compound used in ceramics as a low. Desktop insight 1c substitute wollastonite for whiting. As a service to our customers, we had a qualified, independent agency do an analysis of a sampling. Calcium borate ca 3 bo 3 2, also called gerstley borate citation needed, is a bluish white crystal with a very defined structure. As a control composition for this study 26 percent gerstley borate was used in. If we take some alumina out because it seems too high the glaze begins to craze as we approach 0. It s like trying to hit a moving target when deciding on what chemical formula to use when developing a substitute. To generate a replacement, a new material was created. 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.
Gerstley borate is not a mineral but an aggregate of colemanite hydrated calcium borate hydroxide, ulexite socalled television stone, sodium calcium borate, some hectorite lithium magnesium sodium montmorillonite. Borates article about borates by the free dictionary. A hydrated form occurs naturally as the minerals colemanite, nobleite and priceite. This recipe is a common gerstley borate clear base used from 04 all the way to cone 6. It can be prepared by reacting calcium metal with boric acid. No common natural material comes anywhere close to melting like gerstley borate gb, it is completely fluid, ultraclear and glossy at cone 06. Gerstley borate official composition page from laguna clay. Gerstley borate na20 2ca0 5b203 16 h20 a sodium, calcium borate unprocessed ore used as a low temperature flux in clay formulas. Calcium borate also called gerstley borate, is a bluish white crystal with a very defined. Gerstley borate rocky mountain clay clay for teachers. 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. Gerstley borate is a calcium borate ore containing the mineral ulexite. Aug 30, 2017 it is high in sodium and lower in silica than other feldspars and melts around cone 6.
Borates result either from the reaction of a base with a boron oxyacid or from the melting of boric acid or boron. You can find all our products available to buy online, as well as in our three branches. On an oxide level, gerstley borate is an inexpensive and generous contributor of boron and this is the fundamental reason for its use boron is the magic behind almost all low fire glazes. 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. Mgo in talc or dolomite, li 2 o in lithium carbonate, even substitute more than one at the same time e. Gerstley borate dose any one out there have the latest formula some of my glazes. These compounds are salts of the oxyacids of boron b, such as boric acid, h3bo3, metaboric acid, hbo2, and tetraboric acid, h2b4o7. A publication of digitalfire gives a number of different gerstley borate compositions. As a control composition for this study 26 percent gerstley borate was used in floating blue. The borax chemical formula is also commonly written in a more compact notation as na 2 b 4 o 7 10h 2 o. 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. Sodium borate can be obtained in high purity and so can be used to make a standard solution in. At higher temperatures the recipe trends toward less kaolin to more silica and a little less gb e.
Substituting gerstley borate in floating blue youtube. Gerstley borate is a sparingly soluble greywhite mineral that may, at high concentrations, cause damage to. Frits are commonly used for this purpose along with gerstley borate and soluble materials like soda ash and borax. 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. Lithium oxide li2o is the lightest weight, smallest particle size and most powerful of. No common natural material comes anywhere close to melting like gerstley borate gb. 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 same percentage of gillespie borate was substituted, yielding floating blue revised. Pyrophyllite pyrax hs 50 lb bag kyanite 325 mesh 50 pound bag htp ball clay 50 pounds dry. This is a conglomerate mineral made up primarily of colemanite, ulexite and hectorite. Gerstley is a natural borate similar to but not interchangeable with colemanite on a 1 to 1 basis. A sodiumcalcium borate compound used as a low temperature flux which. Dip treatments a number of log home manufacturers dip their logs in a solution of borate before they are shipped to the customer. Browse for more products in the same category as this item.
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