I like to do a lot of experiments formulating translucent cone 6 porcelain bodies and wanted to show the differences in translucency of kaolins.
I use this recipe with Grolleg and did not compensate for more refractory kaolin's when mixing up test batches, but from doing various tests in the past these results seemed close enough to show the differences.
Cone 6 Porcelain
20 Silica 325 mesh
20 G-200 feldspar
1 Veegum T
2 Frit 3134
For the test tiles I give the percentage of titanium and iron that the kaolins contain, referencing digitalfire.com, with each sample because:
Titanium (TiO2) affects translucency and color.
Iron (Fe2O3) affects color, and less so translucency.
Tiles are approximately 3/32" thick (2.4 mm), fired in an electric kiln.
Back lit with led bulb.
Left to right:
New Zealand Halloysite (kaolin)
TiO2___0.05% 2nd lowest
Fe2O3_ 0.25% Lowest
Fe2O3_ 0.70% 2nd highest
TiO2___0.37% 2nd highest
Fe2O3_ 0.79% Highest
Fe2O3_ 0.50% 2nd lowest