Calcium Borate Frit - 1kg
Good for Copper blue and Manganese purple glazes. Raw materials are weighed, melted together and ground to produce a powdered glass. Frits are storehouses of oxides which are both stable and predictable.
They are more dependable in chemical composition than many raw materials. Using a frit as part of a glaze gives more consistent results and the batch recipe will be considerably simplified.