|Monthly Tech-Tip |
Modified: 2017-06-21 13:54:32
You can make a black glaze at cone 10R using only 1% black stain in a 100% calcine:raw mix of Alberta Slip
|Alberta Slip 1000F Roasted||50.00|
|Mason 6666 or 6600||1.00|
Alberta Slip is a great base for black glazes at cone 10 reduction, only 1% black stain is needed to obtain a jet black glossy. Increasing amounts of stain up to 5% move toward a matte black for Mason 6600 (they remain glossy for Mason 6666). Adding 5-10% black stain and 5-7% iron produces a crystalizing intense gunmetal black. Mixtured additions of Mason 6600:6666 (e.g. 1:1, 2:2) produce metallic surfaces.
Like other high-percentage Alberta Slip glazes, you must use a mix of calcined a raw powder. See the preparation page at http://albertaslip.com for more information.
Alberta Slip (50:50 calcine:raw mix) with 1, 2, 3, 4 and 5% added Mason 6666 black stain. Fired at cone 10R. Semi-gloss blacks are produced. Increasing stain percentage above about 3% does not darken the color appreciably.
Roasted Alberta Slip (right) and raw powder (left). These are thin-walled 5 inch cast bowls, each holds about 1 kg. I hold the kiln at 1000F for 30 minutes. Why do this? Because Alberta Slip is a clay, it shrinks on drying (if used raw the GA6-B and similar recipes will crack as they dry and then crawl during firing). Roasting eliminates that. Calcining to 1850F sinters some particles together (creating a gritty material) while roasting to 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.
Plainsman Cone 10R Firing
Six-step oxidize-at-end schedule to 2372F
GA10-B - Alberta Slip Tenmoku Cone 10R
You can make a tenmoku from Alberta Slip by adding only 2% iron oxide and 5% calcium carbonate
Alberta Slip Glaze Recipes
Alberta Slip is a substitute for Albany Slip that has gained a life of its own so that there are now many glazes based specifically on it.
Albany Slip successor - a plastic clay that melts to dark brown glossy at cone 10R, with a frit addition it can also host a wide range of glazes at cone 6.
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|By Tony Hansen|
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