|Monthly Tech-Tip |
A high temperature reduction glaze made by adding a small amount of iron oxide to a magnesia matte base glaze
Usually describes a bamboo colored matte glaze (especially in reduction stoneware). These are normally achieved in a magnesia white matte by adding a small amount of iron (0.5-1%) and possibly some tin oxide opacifier.
Refired to 1950F. The recipe is very flux heavy (high feldspar) dolomite:spodumene matte, zero silica, 4% tin oxide and less than 1% iron oxide. Sounds like crystallization territory. The plate on the left is the way it normally fired. On the right that way it started firing. The mug on the bottom has been refired at 1950F in oxidation and the color is back. The tin is likely a catalyst for the crystallization that occurred in the original result. Could be a fragile mechanism. Anyway, a period of oxidation at the end of the reduction firing should solve this.
G2571A - Cone 10 Silky Dolomite Matte Base Glaze
A cone 10R dolomite matte having a pleasant silky surface, it does not cutlery mark, stain or craze on common bodies
GR10-J1 - Ravenscrag Cone 10R Bamboo Matte
Plainsman Cone 10R Ravenscrag Slip based glaze. It can be found among others at http://ravenscrag.com.
Dolomite matte glazes have the potential to be very silky and pleasant to the touch, while at the same time being hard, durable and non-crazed (if they are formulated correctly).