This site includes a number of glaze tests carried out using Ian Currie's grid method, as outlined in "Revealing Glazes".
The purpose of these tests is to explore the effects of varying alumina and silica for a given set of flux materials. The grids are laid out in a 5X7 arrangement, and each line, whether vertical or horizontal, represents a line blend, with silica increasing as you go across the tile from left to right, and kaolin (as the alumina source) increasing as you go from bottom to top.
Each set of glazes is based on a given flux combination, which is represented by Corner C, glaze 31. This glaze has flux materials only; all the other glazes have both flux materials and added silica and/or kaolin.
For much more detail about this system of glaze exploration, visit: Ian Currie's website
Ferro Frit 3134 30%; Nepheline Syenite 30%; Whiting 20%; Talc 20%, over black slip:"Talc Set"
Ferro Frit 3134 46%; Custer Feldspar 38%; Talc 9%; Whiting 7%: Ron Roy/John Hesselberth Glossy Base Glaze 2 Family Set
Cobalt Green series (cobalt and rutile added):
Ferro Frit 3134 100% plus 2% alumina oxide (added to fluxes)
Ferro Frit 3134 100% plus EPK 30% (added to fluxes)
Ferro Frit 3134 100% plus EPK 10% (added to colorants)
Ferro Frit 3134 90%, Spodumene 10%
Ferro Frit 3134 90%, Wollastonite 10%
Color response series
Ferro Frit 3110 68%; Whiting 26%; Zinc 2%; (with Copper Carb 2%)
Ferro Frit 3134 30%; Nepheline Syenite 30%; Whiting 20%; Talc 20%, on porcelain:"Talc Set"
Ferro Frit 3134 30%; Nepheline Syenite 30%; Whiting 20%; Talc 20%, on B3 Brown:"Talc Set"
Custer Feldspar 40%, Strontium Carbonate 30%, Zinc Oxide 20%, Spodumene 10%, plus Nickel Oxide 2%
Ferro Frit 3134 46%; Custer Feldspar 38%; Talc 9%; Whiting 7%: Ron Roy/John Hesselberth Glossy Base Glaze 2 Family Set
Currie grids by John Post, barium blues, alkaline greens, slate blues
Currie grids by Kathy Greaves, Talc Set and Roy/Hesselberth Glossy Base Glaze 2
Currie grids by Debbie Engle, Talc Set
Currie grids in pursuit of cobalt greens, page 1
More Currie grids in pursuit of cobalt greens, page 2
Tips for (relatively) painless testing