Ferro 3110 (crackle glaze) is a high soda-silica frit containing a very low percentage of borate (boric acid). 

Composition:
2.3%         K₂O         Potash
15.3%       Na₂O       Soda
6.3%         CaO        Calcium
3.7%         AL₂O₃     Aluminate
2.6%         B₂O₃       Borate
69.8%       SiO₂        Silica Oxide

Fusion Temperature: 1490^o F

What is frit? 
Frit is ceramic chemicals that have been melted together and cooled rapidly (shattered), then ground to a fine powder.  The purpose is to render soluble materials insoluble for workability and stability in glaze and clay formulas.  Frits are always used as a flux in a formula even though they also contain percentages of alumina and silica in combination with common flux materials.

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