|Monthly Tech-Tip |
Modified: 2019-03-13 15:14:25
Plainsman Cone 6 Alberta Slip based glaze. It can be found among others at http://albertaslip.com.
|Alberta Slip 1000F Roasted||40.00|
|Ferro Frit 3134||20.00|
Works well on all types of bodies, very reliable.
For mixing instructions please see the master recipe, GA6-A.
This is Alberta Slip (GA6C) on the left. Added frit is melting the Alberta Slip clay to it flows well at cone 6 and added rutile is creating the blue variegated effect (in the absence of expensive cobalt). However GA6D (right) is the same glaze with added Tin Oxide. The tin completely immobilizes the rutile blue effect, it brings out the color of the iron (from the rutile and the body).
The referred to surface is the outside of this large bowl. The base glaze (inside and out) is GA6-D Alberta Slip glaze fired at cone 6 on a buff stoneware. The thinness of the rutile needs to be controlled carefully, the only practical method to apply it is by spraying. The dramatical effect is a real testament to the variegating power of TiO2. An advantage of this technique is the source: Titanium dioxide instead of sourcing TiO2 from the often troublesome rutile.
Roasted Alberta Slip (right) and raw powder (left). These are thin-walled 5 inch cast bowls, each holds about one kg. I hold the kiln at 1000F for 30 minutes. Why do this? Because Alberta Slip is a clay, it shrinks on drying. Roasting eliminates that, a 50:50 raw:roast mix works well for most recipes having high percentages of Alberta Slip. And 1000F? Calcining to 1850F sinters some particles together (creating a gritty material) while 1000F produces a smooth, fluffy powder. Technically, Alberta Slip losses 3% of its weight on roasting so I should use 3% less than a recipe calls for. But I often just swap them gram-for-gram.
GA6-A - Alberta Slip Cone 6 Amber Base Glaze
An amber-colored glaze that produces a clean, micro bubble free transparent glass on brown and red burning stonewares.
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