"FSCG1" Firing Schedule

Shimbo Crystal Schedule 1

A very quick rise, late in the firing, to target cone is essential when growing crystals. The glazes used for this are very alkaline and leach from the porcelain the one thing that will really ruin your crystals: alumina. The more time the kiln spends at or around your porcelain’s vitrification temperature, the more alumina will be leached. The more alumina, the stiffer the melt of the glaze. The stiffer the melt, the fewer if any crystals you will get.
I’ve found that so long as I can make the last 40°C/~100°F in 1.5 hours or less, I’m fine. More than that ... time to replace the elements, or use the kiln for non-crystalline items.

No kiln will be able to achieve one or more of these rates of climb or drop. And, all but very small or thin-walled ware would crack. Fara is saying above that the degree to which it is possible will determine how well crystals will grow.

Step	°C	°F	Time
1	100°C/hr to 250C	180°F/hr to 482F	2:32
2	200°C/hr to 500C	360°F/hr to 932F	3:47
3	500°C/hr to 1270C	900°F/hr to 2318F	5:19
4	999°C/hr to 1100C	1798°F/hr to 2012F	5:29
5	10°C/hr to 1075C	18°F/hr to 1967F	7:59

Start temperature assumed: 25°C or 75°F
"Fahrenheit degrees" is not the same as "degrees Fahrenheit". A 100° reading on a Fahrenheit thermometer is equal to a 37° reading on a Celcius thermometer. But "100 Fahrenheit degrees of temperature change" is equivalent "55 Celsius degrees of change". That is an important distinction to understand the above temperature conversions.

Related Information

Links

Recipes	VESUCG - Vesuvius Crystalline Glaze Cone 7-9 - Titanium-free with whiting, magnesium carbonate
Recipes	TNF2CG - Tin Foil II Crystalline Glaze Cone 6-9 - Dolomite, tin, titanium variant
Recipes	FAAO - Fa's All-Opaque Crystalline Glaze Cone 8-10 - Opaque surface (crystals and ground), high dolomite and titanium.
Recipes	GRNTCG - GRANITE Crystalline Glaze Cone 8-10 - High titanium variant
Recipes	GBCG - Generic Base Crystalline Glaze Cone 6-10 - Almost all other Frit 3110 recipes are based on additions to this
Typecodes	Oxidation Firing

By Tony Hansen
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