GA6-C (left) and GA6-E (right) at cone 6 oxidation. GA6-E adds 4% spodumene to GA6-C, which contains 4% rutile (the base is 80% Alberta Slip and 20% Frit 3134). Notice how the spodumene suppresses the large pale, overly variegated areas that commonly develop in GA6-C, producing a more uniform blue.
Why? The small spodumene addition introduces Li2O along with Al2O3 and SiO2, changing the melt chemistry and therefore the crystallization and phase-development behavior of the rutile/iron-bearing glaze during cooling. Thus it is safer to regard spodumene as modifying the titanium-related crystallization rather than simply reducing it. Like GA6-C, GA6-E requires a slow-cool firing schedule to develop the rich blue (e.g. C6DHSC). Both look best on darker-burning bodies.
| Typecodes |
Floating Blue
A popular cone 6 glaze that employed Gerstley Borate, it was very troublesome to use and to fire. Much work has been done to create alternative recipes. |
| Glossary |
Rutile Blue Glazes
A type of ceramic glaze in which the surface variegates and crystallizes on cooling in the presence of titanium and iron (usually sourced by rutile) |
| Recipes |
GA6-C - Alberta Slip Floating Blue Cone 6
Plainsman Cone 6 Alberta Slip based glaze the fires bright blue but with zero cobalt. |
| Materials |
Spodumene
Spodumene is a lithium sourcing feldspar, an alternative to lithium carbonate to supply Li2O to ceramic glazes. Contains up to about 8% Li2O. |
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