Monday, April 4, 2011

Putting those the test

Lots of test tiles to choose from, so I started with my favorites. I invariably gravitate around metallic glazes. That's just me. I like the shine, the depth, the warm colors of copper. If a glaze gets completely reduced to copper metal, no matter the expected color, I am happy as a clam, doing the little "I got copper" dance around the reduction chamber.
For this round, I tried Red Luster, which requires heavy reduction (even better in-kiln), Irene's Black/Copper, which is heavy in manganese, and Silver White, a silver nitrate glaze. I also included two old favorites to try alone or in combos, Glassy Copper Sand (GCS) and Turquoise Crackle (TC) (which never gave me turquoise or crackles by the way, so I suspect I messed up the recipe somewhere).
Silver White glaze was the big unknown. It has silver nitrate, a chemical sensitive to light. I prepared the batch when I fired the test tiles last week. I kept it in the dark surrounded in aluminum foil. A week later, I took a peek and it still looked good, unlike a former batch that had turned black (no foil). It pays to be careful. Test tile was ok but not great. A good silver nitrate glaze will give you a smooth shiny quicksilver color. Interestingly the glaze turned out better on my pot then on the tile ! And it works great on top of Irene's Black/Copper. See Bolted Tri-fold and Silver Tri-fold.
Red Luster gave a rusty appearance with some good copper flashes and a few iridescent small patches. It contains red copper oxide which tends to float on top of the glaze, so applying the glaze requires constant stirring. Next time, I will try in-kiln reduction.
Irene's Black/Copper deserves its name completely. Pretty much black, safe for some copper flashing with heavy post-firing reduction. Very nice in combination with a shiny glaze like Silver White. Gold luster would look good as well. On my to-do list.
Combining GCS and TC gave some interesting results. TC has a smooth, slightly bumpy texture, while GCS is heavy on copper flashes (at least in my kiln!). The two together retain the slight bunpy texture while displaying varying degrees of copper flashing. Me like it very much ! 

Asymmetric Tri-fold
(fired twice)
Glassy Copper Sand (main panel);
Glassy Copper Sand on top of Turquoise Crackle (small panels)

Copper Tri-fold
Glassy Copper Sand;
Gold leaf (buttons)

 Bolted Tri-fold
Red Luster;
Silver White (plates)
 Silver Tri-fold Irene's Copper/Black;
Silver White on top of Irene's Copper/Black (rim)

 Tall Square Vase  Glassy Copper Sand on top of Turquoise Crackle (square bottom);
White Cackle (top)

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