Author: mattfiske

Limestone Black Glazes

Not exactly Oil Spots in the truest sense, these two variations were concocted and tested along with the rest of my oilspots glazes. Both of these recipes utilize some local dolomitic limestone I found and incorporated into the recipes. If you want to re-create these, using a mix of 1/2 and 1/2 Dolomite and Limestone will get you very close.

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Dolomitic Limestone from Cache Valley, UT

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Thrown and Stamped Fish Cup

Shizuku Yuteki Variation

Here’s another Oil Spot I put up on Glazy.org.

You might notice that this one has a significant addition of Cobalt, half and half Custer (Potash) and F4 (Soda) Feldspars, calcined talc, and 2% Manganese. Typical that I changed too many things to give a really useful side-by-side comparison. But I suppose when I’m coming up with new variations, that’s always been my style.

2 Shizuku Yuteki Variation
Left: Underfired and immature. Cone 9/10. Right: Super long and hot cone 12 firing, with plenty of peak soak time.

Some observations on this one:

Cobalt goes a long way and pretty dramatically alters an oilspot. With aΒ  .25%-.5% addition you get a nice shift from brown and russet glaze matrix to a darker solid black glass. Beyond 1% you can get some really nice silvery qualities to the spots. The drawback is that the more you add, the more refractory the glaze tends to get – and the longer it takes for the glazes to heal.

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