Aventurine Glaze Refined
firing to cone 10 in oxidation
slow downfire at 50 deg F an hour in the interval 1850 deg F to 1700 deg F
slow downfire at 25 deg F an hour in the interval 1700 deg F to 1650 deg F
One hour hold at 1650 deg F
Derivation
The glaze, iron_8_R_C10_2 had sparkly gold crystals on one wall of the pot, a lovely aventurine glaze, yet only with a thick application. This refinement of that glaze shown here, iron_8_R_C10_8 also is high in alkali metals and in particular is high in Li2O. It has the same alumina of .54, with a silica alumina ratio of 5, as that glaze. The change is that some of the MgO is replaced by CaO, and as the prior glaze seemed capable of absorbing a rather large amount of Fe2O3, iron also is increased.
As is obvious from the numbering of the glazes, there are 5 additional perterbations of the glaze in addition to this one. All of those glazes are equally high in alkali metals, with similar alumina, silica and iron, and share the ability to absorb large quantities of iron. They all have a lusterous surface showing metallic surface artifacts. Missing however are the sparkly scintilating gold flecks in the surface in which this glaze is covered.
The glaze iron_8_R_C10_8
a bowl diameter ~4 inches
 |
 |
 |
detailed close up's of glaze