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Making a Blue Bottle

Today we continue our blue bottle project with the addition of a beautifully mottled blue glaze of my own making. This particular glaze is formulated for US ingredients, so if you substitute with other local ingredients, you should do some firings on test tiles first.

The Brilliant Ink Blue Glaze
Frit 3134 25.0
Feldspar G200 20.0
SGP Ball Clay 20.0
Zinc Oxide 10.0
Cobalt Carbonate 1.5
Cobalt oxide 1.5

How to Glaze
Bisque your slip cast bottles to about 010 (1652o F, 900o C). This will still leave them soft enough to sandpaper out any unevenness that may surface if your mold was not perfect. Pour some glaze into the bottle and pour out again, back into your bucket. If you have made enough glaze (probably unlikely), you can then dip the whole bottle with the opening facing down into the glaze. Wipe the bottom with a sponge. Alternatively, pour glaze over the bottle using a cup or other vessel, until it is covered in the way you want. Glaze to a medium thickness. If applied too thinly, the glaze will become transparent. You may want to to wax or shellac the bottom to make wiping off the excess easier. (The bottle will stick to the kiln shelf if you don't...). Fire these bottles in any kiln, in oxidation or reduction, to cone 4. Another option could be to glaze the interior with a clear glaze, especially if you were thinking of using these bottles for foods or liquids, as leaching of cobalt cannot be discounted in this particular glaze, although I believe it would be unlikely. Get a clear glaze on the midfire glaze page (but be sure to test for glaze fit first).

Copper Red Glaze Alternative

Silica 30.8
Feldspar G200 27.3
Whiting 12.8
Frit 3134 12.2
Tin Oxide 7.8
Copper Oxide 7.0
Kaolin 5.6
Dolomite 1.9
Bentonite 1.0
Red Iron Oxide 0.5

Fire this glaze in a gas kiln in a strong reduction atmosphere to cone 4 and cool in reduction to cone 1.

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