GC106 - GC106 Base Crystalline Glaze

Modified: 2022-10-13 21:46:49

Cone 8-10 - Most other GC106 recipes are based on this.

Material	Amount	Percent
Frit GF 106	70.00	71.4
Zinc Oxide	25.00	25.5
Silica	3.00	3.1
98.00		100

Notes

From Crystal Glazes Book 2 by Fara Shimbo, page 68.

This is the most basic crystalline glaze recipe I know for use with this frit. It requires a slightly higher fire than bases made with the Ferro 3110 frit (it works excellently at cone 10).

Glass Coatings and Concepts' Frit #106 (formerly General Color's GF 106) is in common use in the United States as a replacement for Pemco's 286 frit. As with Ferro Frit 3110, there are hundreds of recipes for glazes using this frit, although the "average" base - 70 frit, 25 zinc oxide, 5 silica - works just fine for me. I lower the silica to 3% and add 2% titania for bigger crystals.

Note that this glaze is much higher in silica than any of the previous glazes. Also, it's silica to alumina ratio, at 23:1, is only about half those of the others, making this glaze higher in alumina also. This makes for a much stiffer melt. Because of this, a 106 glaze, without the addition of other fluxes, requires a higher fire than the others. It wants a true D10 and works well at D11 too. It is extremely underfired at D7 and only a marginal performer at D9.

This base can give extremely brilliant colors; I've had particular success with red copper oxide. I've also noticed that cobalt is far less likely to felt up when used with this glaze, even when a large amount of colorant is used. Mixtures incorporating ilmenite and/or rutile work very well with this recipe, giving very large, quickly growing crystals. The crystals do not show the variation in shape one sees with the Ferro 3110 based glazes, in my experience. Maybe I just haven't experimented enough.

Crystals do form very fast, however, and I have seen them attain an entire centimeter in diameter in as little as fifteen minutes.

Related Information

Vase by Chatt McGonagill

GF-106 crystal base with 3% red iron oxide, 0.5% manganese dioxide and 0.1% cobalt carbonate.‌

Links

Firing Schedules	GC106 Base for Crystalline Glazes By Fara Shimbo
Typecodes	Crystalline Glaze Recipes Fara Shimbo These are from Fara's Crystal Glazes books 1 and 2. Most are the frit 3110, zinc, silica base recipe (50:25:25) with small material additions at the expense of silica.

Mechanisms

Glaze Color	The opacity of the ground of this glaze depends very heavily on the composition of the clay body upon which the glaze is used. The ground is transparent on most porcelains; on some stonewares such as B-Mix and and Loafer's Glory, the ground is opaque and the color generally darker.

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