GR10-E - Alberta Slip:Ravenscrag Cone 10R Celadon

Modified: 2023-10-31 23:48:28

A celadon recipe affording slurry and fired properties control (because proportions of raw and calcined materials and frit can be adjusted)

Material	Amount
Alberta Slip 1000F Roast	47.50
Ravenscrag Slip	47.50
Ferro Frit 3134	5.00
100.00

Notes

This is a celadon that you can tune to your needs. It works well on dark and light stonewares and porcelains. Adjust the proportions of Alberta Slip to Ravenscrag Slip to fine-tune the color (more Ravenscrag for lighter color). Adjust the amount of frit to tune the amount of gloss and melt fluidity. Fine tune the thermal expansion by changing the frit (e.g. frit 3134 for higher expansion, 3249 for lower, 3124 for nuetral).

Since this glaze is 90% clay, roast half of the Alberta Slip complement to reduce the drying shrinkage (for application to bisque ware). If applied to leather-hard ware it should be OK as to use raw Alberta and Ravencrag Slips.

Related Information

GR10-E Ravenscrag:Alberta Slip with 10% calcium carbonate

At cone 10R this produces an overly melted glaze. It also crazes.

Ravenscrag GR10-E celadon glaze

(50:50 Ravenscrag Slip:Alberta Slip) at cone 10R on porcelain (right) and stoneware (left).

GR10-E 50:50 Alberta Slip:Ravenscrag Slip celadon at cone 10R

On a white stoneware and a porcelain. The glaze is transparent, it has depth and varies in shade according to thickness, breaking to a much lighter shade on the edges of contours.

Ravenscrag Alberta Slip Celadon mug by Tony Hansen

The outside glaze on this cone 10R mug (made of Plainsman H550) is G2881B, simply an Alberta Slip:Ravenscrag Slip 50:50 mix (the Ravenscrag Slip portion was roasted). 5% Ferro Frit 3134 was added to get a little better melting (to produce a high gloss). This produces a good celadon with great working and application properties. Inside glaze: Pure Ravenscrag Slip (mixed 50:50 roast and raw).

Roasting Alberta and Ravenscrag Slips at 1000F: Essential for good glazes

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.

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By Tony Hansen
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