{"title":"Gillespie Borate as a Substitute for Gerstley Borate","description":"\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cb\u003e\u003cspan style=\"font-size: 14.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eGillespie Borate: A Substitute for Gerstley Borate in Ceramic Glazes and other ceramics applications:\u003c\/span\u003e\u003c\/b\u003e\u003cspan style=\"font-size: 14.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eCeramic glazes play a vital role in enhancing the beauty, functionality, and durability of ceramic pieces. Traditionally, glazes have been formulated using various raw materials, including boron compounds like Gerstley Borate. However, due to the unavailability of Gerstley Borate in recent years, potters and ceramic artists have been seeking alternative boron sources. One such substitute gaining popularity is Gillespie Borate. IT is an excellent replacement for Gerstley Borate in ceramic glaze recipes and other applications.\u003cbr\u003e\u003c\/span\u003e\u003cb\u003e\u003cspan style=\"font-size: 14.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eUnderstanding Gerstley Borate:\u003c\/span\u003e\u003c\/b\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eGerstley Borate, a natural mineral, has been a staple in ceramic glaze recipes for many years. It contains a significant amount of boron and acts as a flux, helping to lower the melting point of glazes, increase their fluidity, and promote the formation of glossy surfaces. Gerstley Borate also contributes to the development of unique color effects and crystalline structures, making it a sought-after ingredient in ceramic art.\u003cbr\u003e\u003c\/span\u003e\u003cb\u003e\u003cspan style=\"font-size: 14.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eGillespie Borate:\u003c\/span\u003e\u003c\/b\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eGillespie Borate is a boron-rich material that is created to mirror the chemical composition of Gerstley Borate. It has gained attention as a potential substitute due to its comparable chemical composition and fluxing properties. Potters and ceramic artists have embraced Gillespie Borate as a viable alternative, allowing them to recreate familiar glaze effects and achieve desirable outcomes in their work.\u003cbr\u003e\u003c\/span\u003e\u003cb\u003e\u003cspan style=\"font-size: 14.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eAdvantages of Gillespie Borate:\u003c\/span\u003e\u003c\/b\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eFluxing Properties: Like Gerstley Borate, Gillespie Borate acts as a flux, helping glazes reach their desired melting point. It promotes the flow of glazes, leading to smoother surfaces and reducing the risk of pin-holing or crawling. It is a blended material so it actually is more consistent than the notoriously variable Gerstley Borate.Consistency -- Manufactured from high purity refined raw materials, Gillespie Borate™ is highly \u003cb\u003econsistent from batch to batch.\u003c\/b\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cul type=\"disc\"\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l0 level1 lfo1; tab-stops: list 36.0pt;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eOxide Match -- Virtually identical to Gerstley Borate, this product requires no adjustment to formula and no extra additives are needed.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l0 level1 lfo1; tab-stops: list 36.0pt;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eMineral Match -- Gillespie Borate™ provides the same minerals to the glaze as Gerstley Borate, thus imparting the same glaze activity, texture and effects.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l0 level1 lfo1; tab-stops: list 36.0pt;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eParticle Size Match -- As a -200 mesh material, Gillespie Borate™ combines well with other glaze raw materials.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l0 level1 lfo1; tab-stops: list 36.0pt;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003ePlasticity Match -- A high colloid and clay content gives the plasticity necessary for many applications.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l0 level1 lfo1; tab-stops: list 36.0pt;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eReduced Glaze Defects -- Our laboratory studies indicate that Gillespie Borate™ gives increased glaze surface smoothness and a reduction in crawling and pinhole defects.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l0 level1 lfo1; tab-stops: list 36.0pt;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eLower In Off-Color Impurities -- As a refined blended material, Gillespie Borate™ contains few impurities and produces brighter glazes and colors.\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cb\u003e\u003cspan style=\"font-size: 14.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eEase of Use and Applications for Gillespie Borate:\u003c\/span\u003e\u003c\/b\u003e\u003cspan style=\"font-size: 14.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eGillespie Borate can be used in glaze recipes in a similar manner as Gerstley Borate. Its comparable chemical composition allows for easy substitution, making it a convenient alternative for artists already familiar with Gerstley Borate glazes. But always test test test when using a new material in your formulas!\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eVersatility: Gillespie Borate offers a wide range of applications in glaze recipes. It enables the creation of glossy, transparent glazes as well as mattes and crystalline surfaces, allowing artists to explore various aesthetic possibilities.\u003c\/span\u003e\u003c\/p\u003e\n\u003cul type=\"disc\"\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l1 level1 lfo2; tab-stops: list 36.0pt;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eApplications\u003cbr\u003eRaku, Earthenware, Stoneware and Porcelain -- Excellent over a wide temperature range from below cone 06 to cone 10\u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l1 level1 lfo2; tab-stops: list 36.0pt;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eSpecial Effects -- Excellent glaze texture and activity for specialty glazes.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l1 level1 lfo2; tab-stops: list 36.0pt;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eColored Glazes -- GB works well with most pigments and has an exceptionally wide color palette.\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cb\u003e\u003cspan style=\"font-size: 14.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eAvailability:\u003c\/span\u003e\u003c\/b\u003e\u003cspan style=\"font-size: 14.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eThe Gerstley Borate mine is exhausted and will no longer be available. Gillespie Borate is now available here at Sheffield Pottery. Its accessibility ensures that artists can continue experimenting with boron-rich glaze recipes without disruptions.\u003cbr\u003eConsiderations and Adjustments:\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eWhile Gillespie Borate offers a comparable substitute for Gerstley Borate, it is important to note that some adjustments may be necessary when incorporating it into existing glaze recipes. Due to variations in mineral composition, artists should perform small-scale tests to determine the exact amounts required to achieve the desired results. The glaze's overall balance of ingredients, including silica, alumina, and fluxes, may need to be fine-tuned to accommodate the unique characteristics of Gillespie Borate.\u003cbr\u003e\u003c\/span\u003e\u003cb\u003e\u003cspan style=\"font-size: 14.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eConclusion:\u003c\/span\u003e\u003c\/b\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eThe unavailability of Gerstley Borate has prompted ceramic artists to explore alternative boron sources for their glaze recipes. Gillespie Borate has emerged as an excellent substitute, offering similar fluxing properties and enabling the creation of various glaze effects. Its ease of use, versatility, and availability make it an attractive option for artists seeking to maintain their desired aesthetic qualities in their ceramic work. As the ceramic community continues to adapt to changing material availability, Gillespie Borate provides a reliable solution for artists and potters who rely on boron-rich glazes.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp class=\"MsoNormal\" style=\"mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;\"\u003e\u003cspan style=\"font-size: 12.0pt; font-family: 'Times New Roman',serif; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;\"\u003eOrder yours here from Sheffield Pottery. Quantity discounts are available from small quantities to full pallets and more!\u003c\/span\u003e\u003c\/p\u003e","products":[{"product_id":"gillespie-borate-10-pounds-rmgilbor","title":"Gillespie Borate","description":"\u003cdiv class=\"rm-testing-statement\" style=\"border:2px solid #8a5a00;border-radius:6px;padding:12px 16px;margin:16px 0;background:#fdf6e3;\"\u003e\u003cp style=\"margin:0;\"\u003e\u003cstrong\u003eYou must test before you use it, at any scale.\u003c\/strong\u003e Raw materials, mined or man-made, are not consistent. Color, strength, particle size and chemistry can change from one bag to the next and from one supplier to another, even when the name on the bag stays the same. Before you use this material in a glaze, slip or clay body of any size, mix a small test batch, fire it on your own clay in your own kiln, and check the results.\u003c\/p\u003e\u003c\/div\u003e\n\u003cspan\u003e\u003c\/span\u003e\n\u003ch2 class=\"abz-seo-product\"\u003eGILLESPIE BORATE: 10 pounds: Gerstley Borate Substitute\u003c\/h2\u003e\n\u003ch2 class=\"abz-seo-product\"\u003eGerstley Borate Substitute\u003c\/h2\u003e\n\u003cp\u003eGerstley Borate is no longer available.\u003cbr\u003eUse Gillespie Borate as a substitute.\u003cbr\u003eGerstley Borate was a highly variable material and could be different from batch to batch. Gillespie borate is manufactured to meet the most typical analysis of the Gerstley borate so you should find this to be a perfect substitute and more dependable.\u003cbr\u003ePlease test your formulas before using on your work.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"font-weight: bold; text-decoration: underline;\" data-mce-style=\"font-weight: bold; text-decoration: underline;\"\u003eGillespie Borate Fact Sheet\u003c\/span\u003e\u003cbr\u003e\u003cspan style=\"font-weight: bold;\" data-mce-style=\"font-weight: bold;\"\u003eDescription\u003c\/span\u003e : Gillespie Borate™ is a blended borate mineral for use in glaze formulas replacing Gerstley Borate on a pound for pound basis.\u003cbr\u003eChemical Analysis [Typical]\u003cbr\u003e\u003cimg align=\"\" alt=\"Gillespie Borate Chemical Analysis\" border=\"0px\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0677\/5508\/2050\/files\/gillespie-borate-chemical-analysis.pg.jpg?v=1684313259\" style=\"width: 569px;\" data-mce-style=\"width: 569px;\" data-mce-src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0677\/5508\/2050\/files\/gillespie-borate-chemical-analysis.pg.jpg?v=1684313259\"\u003e\u003cbr\u003e\u003cstrong\u003eFeatures\u003c\/strong\u003e\u003cbr\u003e- Consistency -- Manufactured from high purity refined raw materials, Gillespie Borate™ is highly consistent from batch to batch.\u003cbr\u003e- Oxide Match -- Virtually identical to Gerstley Borate, this product requires no adjustment to formula and no extra additives are needed.\u003cbr\u003e- Mineral Match -- Gillespie Borate™ provides the same minerals to the glaze as Gerstley Borate, thus imparting the same glaze activity, texture and effects. \u003cbr\u003e- Particle Size Match -- As a -200 mesh material, Gillespie Borate™ combines well with other glaze raw materials.\u003cbr\u003e- Plasticity Match -- A high colloid and clay content gives the plasticity necessary for many applications.\u003cbr\u003e- Reduced Glaze Defects -- Our laboratory studies indicate that Gillespie Borate™ gives increased glaze surface smoothness and a reduction in crawling and pinhole defects.\u003cbr\u003e- Lower In Off-Color Impurities -- As a refined blended material, Gillespie Borate™ contains few impurities and produces brighter glazes and colors.\u003cbr\u003eApplications\u003cbr\u003e- Raku, Earthenware, Stoneware and Porcelain -- Excellent over a wide temperature range from below cone 06 to cone 10\u003cbr\u003e- Special Effects -- Excellent glaze texture and activity for specialty glazes.\u003cbr\u003e- Colored Glazes -- GB works well with most pigments and has an exceptionally wide color palette.\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"text-decoration: underline;\" data-mce-style=\"text-decoration: underline;\"\u003eFinding a replacement for Gerstley Borate\u003c\/span\u003e\u003cbr\u003eGerstley borate is a complex ore but a major benefit of the unrefined naturally formed combination of minerals is its ability to produce variegated surfaces in glazes. Potter’s firing electric kilns which have oxidation atmospheres often produce flat static glaze effects much like bathroom tile colors. Carbon based fueled kilns, such as natural gas, propane or wood have the capacity to fire in oxidation, neutral, and reduction atmospheres which can introduce varied glaze colors and surfaces. If it wasn’t for this unique characteristic of Gerstley borate it would have been abandoned when the first series of its faults appeared.\u003cbr\u003eGerstley borate’s wide swings in chemical composition are a factor in finding a direct substitute. It’s like trying to hit a moving target when deciding on what chemical formula to use when developing a substitute.\u003cbr\u003eHowever, Gillespie borate, a product produced by Hammill \u0026amp; Gillespie of New Jersey, has proven to be a reliable one-for-one substitute. In many instances it is difficult to arrive at such a close match as many raw materials are not mineralogically pure when removed from the earth. Any potential substitute has to match on many points and produce the same results in fired glazes.\u003c\/p\u003e\n\u003cp\u003eGerstley Borate has been a valuable glaze constituent for many years and is a key part of many interesting and successful glazes over a range of firing conditions. As the supply has dwindled Hammill \u0026amp; Gillespie's technical staff went to the lab and began experimenting. Beginning with x-ray diffraction to determine the mineral constitution of Gerstley borate and following up with other physical and chemical tests, they fully characterized the material and identified three key characteristics: extended particle size distribution including a colloid fraction, a specific and unique distribution of oxides, and a fired property that promotes a variegated color in many glaze compositions.\u003cbr\u003eTo generate a replacement, a new material was created: Gillespie borate, which is virtually identical to Gerstley borate in terms of physical, mineralogical and chemical composition. Gillespie borate is comprised principally of ulexite (sodium calcium borate), with small amounts of colemanite (calcium borate) and other minerals -- just like Gerstley borate. From a pre-fired perspective the most critical element in the new material is its colloid content. Containing approximately 10% clay-like materials, Gillespie borate disperses well in water and makes a reasonably stable glaze slip in the neat state. Further clay addition at the point of use is required to further improve the stability of the slip and pre-fired properties such as strength and adherence. In the fired state, Gillespie borate is virtually identical to Gerstley borate by virtue of the chemical match of oxide content.\u003cbr\u003eThe special behavior of Gerstley and Gillespie borates that produces the unusual glaze effects results from two mechanisms: immiscibility and solubility. Boric oxide (B2O3), when provided to a glass as a coarse raw mineral (e.g. ulexite), is slightly immiscible with silicate glass matrices, and the differential surface energy of the molten phase drives a mass transfer process along the interface (Gibbs-Marangoni effect) that generates the characteristic variegated texture. The slight solubility of these borates also contributes to the mottled glaze surface via migration of soluble oxides, although this effect becomes exaggerated when mixed glazes are stored for long periods.\u003cbr\u003eWhile Gillespie Borate has the beneficial fluxing and glaze development properties of Gerstley borate, it does not have the variability or impurity levels that characterized Gerstley borate. Gillespie borate is a precise mixture of pure natural minerals and is manufactured under close quality control supervision. Hence, Gillespie borate does not vary over time and is a consistent, reliable raw material. Since Gillespie borate does not contain the impurity levels that provided off-color to Gerstley borate glazes, you may find your glazes whiter and brighter. 2.\u003cbr\u003e\u003c\/p\u003e\n\u003ch2 class=\"abz-seo-product\"\u003e\u003cspan style=\"text-decoration: underline;\" data-mce-style=\"text-decoration: underline;\"\u003eRecommendations for using Gillespie borate\u003c\/span\u003e\u003c\/h2\u003e\n- Do not use excess water in mixing the glaze.\u003cbr\u003e- Store the wet glaze in an airtight container.\u003cbr\u003e- When using any substitute material always test it in a small batch of glaze.\u003cbr\u003e- Test the glaze on the same clay body you will use in production.\u003cbr\u003e- After applying the glaze to several vertical test tiles place them throughout the kiln.\u003cbr\u003e\u003cspan style=\"font-weight: bold;\" data-mce-style=\"font-weight: bold;\"\u003eFootnotes\u003c\/span\u003e\u003cbr\u003e The exact chemical composition of Gillespie borate is proprietary to Hammill \u0026amp; Gillespie. Gillespie borate is a mixture of ulexite (Na2O.2CaO.5B2O3.16h4O) with various clay minerals (aluminum silicates), alkaline earth carbonates and silicates. This material contains approximately 25% B2O3, 23% CaO, 4% total alkali and 31% loss on ignition.\u003cbr\u003e\u003cimg align=\"\" alt=\"Gillespie Gerstley Borate Glaze\" border=\"0px\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0677\/5508\/2050\/files\/gillespie-borate-glaze.jpg?v=1684313276\" style=\"width: 325px;\" data-mce-style=\"width: 325px;\" data-mce-src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0677\/5508\/2050\/files\/gillespie-borate-glaze.jpg?v=1684313276\"\u003e\u003cbr\u003e","brand":"Sheffield Pottery","offers":[{"title":"1 Pound","offer_id":67286210740595,"sku":"RMGILBOR-1","price":3.8,"currency_code":"USD","in_stock":true},{"title":"5 Pounds","offer_id":67286210773363,"sku":"RMGILBOR-5","price":18.25,"currency_code":"USD","in_stock":true},{"title":"10 Pounds","offer_id":45113723584834,"sku":"RMGILBOR","price":35.5,"currency_code":"USD","in_stock":true},{"title":"25 Pounds","offer_id":67286210806131,"sku":"RMGILBOR-25","price":86.25,"currency_code":"USD","in_stock":true},{"title":"50 Pounds","offer_id":67286210838899,"sku":"RMGILBOR50","price":115.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0677\/5508\/2050\/files\/large-Glowmax_clay_dry.jpg?v=1696877281"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0677\/5508\/2050\/collections\/large-Glowmax_clay_dry.jpg?v=1786637850","url":"https:\/\/www.sheffield-pottery.live\/collections\/gillespie-borate-substitute-for-gerstley-borate.oembed","provider":"Sheffield Pottery Inc.","version":"1.0","type":"link"}