Pottery 2018, Glazing Basics
In February 2018 I attended a class across four nights to learn the basics of mixing glazes for cone 6 firing. I have included some basic explanations in the captions of the uploaded images. All glaze samples were fired on Highwater Clays from North Carolina and were fired at cone 6/soft 7. Most were fired in a gas reduction, but there are a few electric oxidization tests. Recipes are in most of the image captions, with the exception of the Pinnell Glaze. Percentages are written to match a 100 gram recipe.
Samples are arranged from left to right as follows: Ellen Buff (mid range with 3% fine mullite), Hestia (high-range with 6% fine mullite, Little Loafer's (mid-range), and Helios Porcelain (high-range, grolleg-based).
Pinnell glaze base, reduction firing, cone 6.
Mild surface texture, satin finish. A beautiful dark speckled base with even mottling.
Pinnell glaze base, oxidization firing, cone 6.
A creamy, warm white with satin finish.
Pinnell glaze base with added colorants: copper carbonate (3) and cobalt (.5).
Retained the satin finish of the base, gorgeous muted blue with metallic mottling.
Pinnell glaze base with added colorants: copper carbonate (3), cobalt (.5), and titanium dioxide (5).
Retained the satin finish of the base, a muted yet lively green with more yellow on the edges and more blue-tinged mottling where thicker.
Larger mixed batch of the Pinnell Green.
Retained all characteristics, including the earthy bronze finish on the two darker clays.
Wright's Water Blue Glaze, reduction firing cone 6, not recommended.
Lithium Carbonate (3), Strontium Carbonate (9), Frit 3110 (59), EPK (12), Flint (17), Bentonite (2)
Colorant: Commper Carbonate (5)
Wright's Water Blue Glaze, oxidization firing cone 6.
True colors, bright turquoise. Still some slight crazing but no mottled purpling from the iron in the clay.
Wright's Water Blue Glaze, reduction firing cone 6.
Base recipe with extra added 5% EPK in an attempt to stabilize the glaze. Still ran badly.
Wright's Water Blue Glaze, reduction firing cone 6.
Second attempt at stabilization. Recipe now with 2 Lithium Carb, 8 Strontium, and 15 EPK.
Wright's Water Blue Glaze, reduction firing cone 6.
Third attempt at stabilization, same recipe but later firing. Still a lovely glaze but not recommended for reduction firing.
Marilee's Lava Glaze Base, reduction firing cone 6, not food safe. Great texture.
Whiting (23.91), custer feldspar (49.73), EPK (13.18), and Flint (13.18).
Colorants (not shown): Titanium Dioxide (11.29) and Silicon Carbide (.34)