|Monthly Tech-Tip |
Modified: 2022-10-13 21:49:04
Cone 6-9 - Dolomite, tin, titanium variant
|Ferro Frit 3110||50.00|
From Crystal Glazes Book 2 by Fara Shimbo, page 66.
Purpose: To alter the shape of the crystals from broad "geranium" petals to narrow "dandelion" or "aster" petals by using tin.
Tin Foil 2 is an excellent low-titanium glaze; in fact, it makes an excellent no-titanium glaze if you just leave the titanium out. On porcelain, it has a very transparent ground, though this does not necessarily hold true on stoneware. I decided to try adding tin to the glaze when I noticed the very interesting effect that chrome-tin pinks had on the crystals; the nearly complete change in character from a flower to a lily pad. Most of this effectis due to chrome, but with chrome being a powerful colorant I didn't want to use it. Tin is generally thought of as an opacifier, but in small amounts like this its only real effect is to change the shape of the crystals, so instead of a daisy, one has a dandelion. Tin Foil 2 crystals are very opaque which makes this an excellent glaze for use with copper colorants. The ground is often slightly yellowish by itself, often varying the color responseof cobalt toward cyan.
Tin Foil has always been an exceptionally reliable glaze for me. I found out that the original would go down to D5 quite by accident one day when the power went out at that temperature. After two hours soaking at 1000°C, I had lovely crystals about 2 cm in diameter. It's been my experience that crystal growth slows down proportionally to the amount of tin in the glaze; so much so that if you add about 4% tin you can grow only a few crystals no more than a centimetre in diameter even after a three-hour soak.
Two cats made with the Tin Foil base and about 4% red copper oxide. Both of these show the lovely green you can get with copper. Both were fired in a gas kiln; the cat on the left was at the edge of a shelf, close to the flame. The cat on the right was in the center of the shelf. Both were cast of White Stallion porcelain.
Shimbo Crystal Schedule 1
Crystalline Glaze Recipes Fara Shimbo
These are from Fara's Crystal Glazes books 1 and 2. Most are the frit 3110, zinc, silica base recipe (50:25:25) with small material additions at the expense of silica.
|Crystal Glaze Variations||Crystals produced by this glaze have many narrow "petals" instead of only a few (or one) large, broad petal. Aster or dandelion shaped crystals, ends are often "frilly."|
|Glaze Color||When used with up to 2% copper carbonate, magnificent true turquoises and cyans result (due to interaction with tin and calcium).|
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|By Tony Hansen|
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