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Gillespie Borate as a Substitute for Gerstley Borate

Gillespie Borate: A Substitute for Gerstley Borate in Ceramic Glazes and other ceramics applications

Ceramic 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.

Understanding Gerstley Borate:

Gerstley 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.

Gillespie Borate:

Gillespie 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.

Advantages of Gillespie Borate:

Fluxing 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 consistent from batch to batch.

 Oxide Match -- Virtually identical to Gerstley Borate, this product requires no adjustment to formula and no extra additives are needed.
 Mineral Match -- Gillespie Borate™ provides the same minerals to the glaze as Gerstley Borate, thus imparting the same glaze activity, texture and effects.
 Particle Size Match -- As a -200 mesh material, Gillespie Borate™ combines well with other glaze raw materials.
 Plasticity Match -- A high colloid and clay content gives the plasticity necessary for many applications.
 Reduced Glaze Defects -- Our laboratory studies indicate that Gillespie Borate™ gives increased glaze surface smoothness and a reduction in crawling and pinhole defects.
 Lower In Off-Color Impurities -- As a refined blended material, Gillespie Borate™ contains few impurities and produces brighter glazes and colors.

Ease of Use and Applications for Gillespie Borate:

Gillespie 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!

Versatility: 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.

 Raku, Earthenware, Stoneware and Porcelain -- Excellent over a wide temperature range from below cone 06 to cone 10
 Special Effects -- Excellent glaze texture and activity for specialty glazes.
 Colored Glazes -- GB works well with most pigments and has an exceptionally wide color palette.


The 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.

Considerations and Adjustments:

While 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.


The 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.

Order yours here from Sheffield Pottery. Quantity discounts are available from small quantities to full pallets and more!
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GILLESPIE BORATE: : 10 pounds Gillespie Borate: 10 Pounds


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Gillespie Borate as a Substitute for Gerstley Borate