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annacondagh

confused over earthenware and glazes

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annacondagh    0

Hi

I am new to pottery i started throwing on a kick wheel in Jan and love it, i have a small manual kiln that operates on a kiln sitter and i was using stone ware and stone ware glazes but I want to change to earthenware as my kiln struggles with the higher temps. Here's my problem, the earthenware clay both white and terracotta I can get tends to have a maturing temperature of 1080 to 1160, the glazes for earthen ware tend to be between 1040 and 1060. I don't have the knowledge or experience yet to make my own glazes so I buy ready made brush on. So do I bisque to the higher clay temp and then glaze at lower temp and if I do this does the bisque ware easily soak the glaze. Many thanks fo any help you can give me, there is much to learn.

Anna

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Dick White    155

With stoneware, the typical bisque vs. glaze temperatures are bisque low (often the same as earthenware) and glaze higher. With earthenware, it is often reversed. Bisque a little higher to solidfy the ceramic and glaze lower. Just use the appropriate cones for each stage.

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Benzine    610

You are correct.  Unlike mid to high fire wares, where you bisque at a lower temperature, and glaze at a higher temperature, low fire you fire hotter for the bisque.  

With mid to high fire, the glaze firing not only melts the glaze, but vitrifies the clay.  With low fire, the higher bisque helps burn out things, that might cause issues/ defects, with the glaze.  Most low fire clay doesn't vitrify, though the glaze can seal them.

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neilestrick    1,381

Many terra cotta bodies will go as high as cone 3/4 before they start to slump, although most people glaze fire them at cone 04. White earthenware bodies won't typically go beyond cone 1, and again most people glaze fire around 04. I would plan on bisque firing at 03 at glaze firing at whatever cone is recommended for the glazes, probably in the 06-04 range.

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Benzine    610

The Amaco glazes I use, for my low fire white, recommend bisque firing to a "Mature 04", then glaze firing to 05.

As a time and money saving effort, I have fired mixed loads plenty of times, and will take glazed wares to 04, with no issues.  I have also single fired wares to 04, also with no issues.  

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