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Gerstley Borate: Overview

There is alarm across the ceramic community in North America about the demise of Gerstley Borate (GB). This situation is of interest to people everywhere because it reveals a fundamental change we need to make in the way we view and use materials. However things are working out in such a way that ceramic artists and small companies may well be better off than before. Further, the promises of a consistent plastic borate are very compelling, promising to give us stoneware bodies and glazes at much lower temperatures.

As of the beginning of 2000 US Borax ceased mining Gerstley Borate because the cost of meeting regulations in the old and small mine exceeded the value of the material.  Material in the sales channel is predicted to last until the 2003 yearend. Although often criticized as a variable and undependable material, Gerstley Borate has been tremendously popular in art glazes at all temperature ranges for many decades. The demise of this material has seen replacement efforts that are quite disproportionate to the amounts that were actually sold. Even US Borax engineers who have long found it a nuisance are reflecting with interest on the flurry of activity surrounding duplication efforts. Frit manufacturers that barely even knew about it are even throwing their equivalent products into the ring. We now have enough experience from these materials and from formulating one ourselves that I can say with some certainty that no one is going to be able to produce the perfect match. It has also become clear that some vendors were rushed to create their products and have overlooked some minor (and even major) details.

On this site we will editorialize about this situation also. Gerstley Borate has bred a generation of boron saturated glazes that have nice visual character (e.g. variegation, crystallization, color saturation) but invariably lack properties like hardness, resistance to leaching, pleasant working properties, and stability. On the other hand, GB makes it possible to make visually lively glazes at cone 3-6 instead of the usual cone 9-11. Thus we all have some things to learn from this situation. I am convinced that your main tool to deal with this is a knowledge of the options. We have created this web site to help you understand what GB was, what the substitutes are, and how this material bred a wilful ignorance of material and oxide knowledge in our educational institutions and among potters. The site tells you how to make your own substitute and adjust it for each glaze. It also touches on the technical Nirvana of glazing: How to use INSIGHT software to remove GB on a glaze-by-glaze basis and fix other problems at the same time.

Parable of Replacement and Substitution by Tig Dupre

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