Modification Date: 2009-05-23 11:15:13
Member of Group: Crystal
Cone 9-10 for brilliant colors
|Frit GF 106||70.0|
|Rate (C)||Temp (C)||Hold (Min)||Step|
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.
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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By Tony Hansen+