An example of how a micro-bubble population in the matrix of a transparent glaze can partially opacify it. If this glaze was completely transparent, the red clay body would show much better. However this is not the fault of the glaze. On a white body it would be more transparent. The problem is the terra cotta body. This is fired at cone 02. As the body approaches vitrification the decomposition of particles within it generate gases that bubble up in to the glaze. A positive aspect of this phenomena that this glaze could be opacified using a lower percentage of zircon.
This type of glaze responds better to opacifier additions.
Glaze opacity refers to the degree to which it is opaque. Opacifiers are powders added to transparent ceramic glazes to make them opaque.
Suspended micro-bubbles in ceramic glazes affect their transparency and depth. Sometimes they add to to aesthetics. Often not. What causes them and what to do to remove them.
|Body decomposition causes glaze bubbles (1065-1120)