|Monthly Tech-Tip |
On a clay test tile this titanium opacified cone 6 oxidation glaze, G1214Z1, looks great. But it is important to recognize that its variegated fired appearance is a combination multiple factors: The chemistry of the glaze, the titanium, quality laydown, the PLC6DS firing schedule, the red M390 clay body and variations in the thickness-of-application. However, the last four of those factors changed with the mug on the right! It is made from buff-burning M340! There are drips from uneven drainage during glazing. The slow cool C6DHSC firing schedule. Notice how it is actually going transparent where very thick. An even laydown was not achieved since the slurry was not properly mixed, it contains calcined kaolin and requires special attention to achieve a thixotropy.
The body is Plainsman M390. Firing is the cone 6 PLC6DS schedule. Each horizontal row is a commonly-used base glaze. The top one is an MgO matte, the next one down is a calcium matte, row 3 is G2926B glossy and row 4 is Ravenscrag Slip+frit. The two mattes behave very differently from each other with the additions of opacifier. Thickly applying an opacified glaze will obviously affect visual character (column 4). Tin oxide fires whiter than zircon (e.g. Zircopax). If you like the G2934 recipe, consider the G2934Y variant for better melting.
A super white powder used in ceramic glazes to variegate, opacify and moderate color.
Refers to the quality of the dried ceramic glaze and how this affects the fired result: e.g. density, hardness, evenness, thickness, etc.
Glaze opacity refers to the degree to which it is opaque. Opacifiers are powders added to transparent ceramic glazes to make them opaque.