|Monthly Tech-Tip |
Modified: 2016-09-11 21:21:50
By adding a little iron to 100% Alberta Slip you can make an iron crystal glaze.
|Alberta Slip 1000F Roasted||50.00|
|Red Iron Oxide||3.00|
Typically this type of glaze is made by adding up to 15% iron oxide to a transparent glaze. However using Alberta Slip, you only need 3% iron (this is an advantage because 10% iron flocculates the glaze, requiring the addition of more water which in turn causes crawling). Adjust the iron to get the amount of crystal development and metallic appearance desired. In reduction the extra iron will flux it more so melting should be good.
This is fired in cone 10R. The effect becomes more intense by 5%. To achieve this same effect using Ravenscrag, which has much less natural iron content, 10% added iron is needed (which is, of course, much messier to work with).
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
G2916F - Cone 6 Stoneware/Whiteware transparent glaze
Crystal clear industrial dinnerware glaze
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.
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|By Tony Hansen|
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