• Materials for Ceramics

Zinc Oxide Raw

Alternate Names: Zinc 88, Zinc 90

Notes

Raw zinc oxide has not been calcined so it has some LOI on firing.

Related Information

Frits instead of raw zinc, lithium, barium, strontium

These materials have many issues. They can create problems in glaze slurries (like precipitates, higher drying shrinkage), cause issues with laydown density and produce fired surface defects (like pinholes, blisters, orange peeling, crystallization). Lithium and barium carbonates have toxicity issues and the carbon burns off during firing (with lithium, for example, 60% of its weight is lost). Yet the oxides that these materials supply to the glaze melt - ZnO, Li₂O, BaO and SrO can be sourced from frits (removing most of the problems and imparting better glaze melting). Fusion Frit F-493 has 11% LI2O, F-403 has 35% BaO, F-581 has 39% SrO and FZ-16 has 15% ZnO. Of course, these frits source other oxides (but such are common in most glazes). Using glaze calculation you can often duplicate the chemistry of glazes while sourcing these oxides from frits. This being said, using the frits is about achieving a quality and avoid defects over concerns about their extra cost. Often the benefits lower the overall cost of production.

Raw and calcined zinc oxides in a crystalline glaze

Zinc oxide calcined (left) and raw (right) in typical crystalline glaze base (G2902B has 25% zinc) on typical cone 6 white stoneware body. This has been normally cooled to prevent crystal development. The melting pattern is identical. Note how badly these are crazed, this is common since crystalline glazes are normally high in sodium.

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