![1 kg Gillespie Borate](http://psh.ca/cdn/shop/files/MGEB3_{width}x.jpg?v=1685805341)
A substitute for mined-out Gerstley borate, a naturally occurring source of boric oxide, promoting early fusion. It is a blend of the same minerals proportioned to preserve the chemistry and working properties of Gerstley Borate. Use it as a 1:1 substitute. Testing first to compare fired results is recommended; some glazes may need minor adjustments.
For more information on Gillespie Borate borate, see the Digitalfire.com Reference Library of ceramic materials.