Transparent glazes — clear, glossy coatings that reveal the body or engobe color underneath — require a perfectly clear, bubble-free glass layer with high surface smoothness.
Application Overview
The glaze must melt completely, flow to an even thickness, release all trapped gas bubbles, and cool to a transparent glass without crystallization. Nepheline syenite contributes to transparent glaze quality through its combination of effective fluxing (ensuring complete melting), high alumina (preventing uncontrolled crystallization that would cloud the glaze), and low iron/titanium (preventing color tint in what should be a colorless glass layer). For transparent glazes, K200 is the preferred grade — its ultra-low Fe2O3 (0.08%) prevents the yellow-brown tint that higher-iron materials would introduce. The 200-mesh particle size ensures rapid dissolution during the glaze firing, reducing the risk of undissolved particles that could scatter light and reduce clarity.
Technical Details & Formulation
Typical transparent glaze using nepheline: 30-35% nepheline K200, 15-20% quartz, 20-25% frit, 10-15% kaolin, 5-10% zinc oxide, plus minor additions of calcium carbonate and other modifiers..
