|Monthly Tech-Tip |
Modified: 2021-03-07 22:30:16
Plainsman Cone 6 Ravenscrag Slip based glaze. It can be found among others at http://ravenscrag.com.
|Alberta Slip 1000F Roasted||38.00|
|Ferro Frit 3134||19.00|
|Ferro Frit 3124||5.00|
|Iron Oxide Red||1.00|
|Copper Oxide Black||0.50|
This was originally discovered as a 50:50 mix of G2917 Ravenscrag Floating Blue and G2908 Alberta Slip Floating Blue. The result is green. The recipe is a combination of the two with slight changes (0.5 cobalt instead of 0.75, 1.0 iron instead of 1.5, 2.5 rutile instead of 3.0).
For mixing instructions please see the master recipe, GR6-A.
The magic of this recipe is the 5% extra frit, that makes the melt more fluid and brilliant and gives the glaze more transparency where it is thinner on edges and contours. The extra iron in the Plainsman P380 (right) intensifies the green glaze color (vs. Polar Ice on the left).
The specks are cobalt oxide agglomerates that were made by slurrying cobalt oxide and bentonite, then crushing it to sizes large enough to make the specks.
Brilliantly glossy. The body is Plainsman Polar Ice porcelain. Firing is cone 6 oxidation. The reduction fired effect is particles (or agglomerates) from one of the raw metal oxides in the recipe (iron, cobalt, rutile; most likely the cobalt). If this glaze were ball milled the effect would be lost. Even though the glaze is so glassy, it is not running down off at the foot. The blue where it thickens on contours is because of the rutile, this can be removed for a truer Celadon effect (if it is not causing the specks).
The outer green glaze on these cone 6 porcelain mugs has a high melt fluidity. The liner glaze on the lower one, G2926B, is high gloss but not highly melt fluid. Notice that it forms a fairly crisp boundary with the outer glaze at the lip of the mug. The upper liner is G3806C, a fluid melt high gloss clear. The outer and inner glazes bleed together completely forming a very fuzzy boundary.
GR6-A - Ravenscrag Cone 6 Clear Glossy Base
This Plainsman Cone 6 Ravenscrag Slip base is just the pure material with 20% added frit to make it melt to a glossy natural clear.
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|By Tony Hansen|
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