|Monthly Tech-Tip |
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The Ravenscrag Slip based burgundy glaze on the outside of these mugs is made by fluxing Ravenscrag with 20% Ferro Frit 3134 and adding 10% Mason 6006 burgundy stain (actually these have a little less stain, about 8%). This stain works better than using raw chrome and tin. This glaze functions very well on porcelains and breaks white on the edges to highlight contours.
Ravenscrag Slip, by itself, produces a silky transparent glaze at cone 10R. It is an excellent base to which to add colorants and modifiers. This is a simple addition of 10% iron oxide (Ravenscrag Slip already contains 2% iron, making about 12% total Fe2O3). It produces a stunning crystalline fired surface on these two porcelains. We can call this a "Beyond-Tenmoku" (crystals happen because of more iron or a slow cooling rate than a Tenmoku). The 12% iron dissolves in the glaze melt during firing, but during cooling in the kiln, the extra 2% precipitates out to produce these surfaces. The iron also acts as a flux in reduction firing, greatly increasing melt fluidity. Take that last statement seriously: The iron is a flux, the glaze will melt much more. So just adding iron oxide to a glossy transparent will wreck your kiln shelves when it runs down off the ware. Ravenscrag Slip does not melt-to-glossy, it has just enough feldspar to fire to a durable surface, making it a more stable host for the iron addition.
|Materials||Ravenscrag Slip 1900F Calcined|
|Materials||Ravenscrag Slip 1000F Roast|
Concentrate on One Good Glaze
It is better to understand and have control of one good base glaze than be at the mercy of dozens of imported recipes that do not work. There is a lot more to being a good glaze than fired appearance.
Ravenscrag Slip is Born
The story of how Ravenscrag Slip was discovered and developed might help you to recognize the potential in clays that you have access to.
g2851H - Ravenscrag Cone 6 High Calcium Matte Blue
Plainsman Cone 6 Ravenscrag Slip based glaze. It can be found among others at http://ravenscrag.com.
GR10-A - Pure Ravenscrag Slip
Ravenscrag all by itself makes a great cone 10 reduction semi-gloss glaze. It also has great working properties.