Leather hard to glaze fired weight difference - Electric Mid&Hi Fired Ceramics2024-03-29T12:07:18Zhttps://cone6pots.ning.com/forum/topics/leather-hard-to-glaze-fired-weight-difference?commentId=2103784%3AComment%3A142018&feed=yes&xn_auth=noInteresting. That 10% loss of…tag:cone6pots.ning.com,2017-05-25:2103784:Comment:1418322017-05-25T23:31:05.316ZNorm Stuarthttps://cone6pots.ning.com/profile/NormStuart
<p>Interesting. That 10% loss of weight would probably be quite different with a different clay and glaze.</p>
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<p>Interesting. That 10% loss of weight would probably be quite different with a different clay and glaze.</p>
<p></p> Fired glazed weights average…tag:cone6pots.ning.com,2017-05-25:2103784:Comment:1420182017-05-25T21:32:30.126ZTom Humphrieshttps://cone6pots.ning.com/profile/TomHumphries
Fired glazed weights average at 760 grams
Fired glazed weights average at 760 grams Thanks Norm that is all helpf…tag:cone6pots.ning.com,2017-04-22:2103784:Comment:1418522017-04-22T21:47:57.503ZTom Humphrieshttps://cone6pots.ning.com/profile/TomHumphries
Thanks Norm that is all helpful information. Lots of variables! I decided to go with my gut feeling that they were a bit heavy. I trimmed a bit more as I had a rather chunky footring. I've recorded the weights of the four plates (average 850g) at leather hard. I will post the fired glazed weights for anyone who is interested.
Thanks Norm that is all helpful information. Lots of variables! I decided to go with my gut feeling that they were a bit heavy. I trimmed a bit more as I had a rather chunky footring. I've recorded the weights of the four plates (average 850g) at leather hard. I will post the fired glazed weights for anyone who is interested. Hi Tom - 100 grams of wet cla…tag:cone6pots.ning.com,2017-04-22:2103784:Comment:1418492017-04-22T17:30:06.365ZNorm Stuarthttps://cone6pots.ning.com/profile/NormStuart
<p>Hi Tom - <strong>100 grams of wet clay should weigh about 52 to 57 grams after it's bisqued or high-fired without a glaze.</strong></p>
<p>Prepared clay is usually 1/3 water by weight. You'll have to weigh a piece of wet clay, then weigh it again to learn how much water weight is lost getting to leather hard.</p>
<p>When you bisque-fire clay it loses another 12.5% of weight as chemical water is released by the kaolin to metakaolin conversion and you'll lose any organics in the clay - so from…</p>
<p>Hi Tom - <strong>100 grams of wet clay should weigh about 52 to 57 grams after it's bisqued or high-fired without a glaze.</strong></p>
<p>Prepared clay is usually 1/3 water by weight. You'll have to weigh a piece of wet clay, then weigh it again to learn how much water weight is lost getting to leather hard.</p>
<p>When you bisque-fire clay it loses another 12.5% of weight as chemical water is released by the kaolin to metakaolin conversion and you'll lose any organics in the clay - so from bone-dry to bisqued you can count on a loss of 13% to 21%.</p>
<p><strong>100 grams of Wet Clay</strong> - 33% = 66 grams - 13% bisque <strong>= 57 grams</strong> or as little as 66 grams - 21% <strong>= 52 grams</strong></p>
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<p><span style="text-decoration: underline;">The weight added by glaze varies enormously</span>.</p>
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<p><strong>Thin ceramic pieces, which don't weigh much, can easily double in weight after they are heavily glazed and re-fired</strong>. A piece bisqued to a higher temperature like cone 03 or 04 will absorb less glaze than one bisqued to cone 06. More of a stiff glaze can remain on a ceramic without running off, so this can load up glaze weight, as can a thick beautiful pool of glaze inside a bowl.</p>
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<p><strong>Glaze adds very little weight to bone china or fine porcelains</strong> because they are first completely densified and made non-porous at Cone 02 to Cone 12 depending on the vitrification temperature of that prepared body. A <strong>very thin</strong> coat of wet glaze, or dry glaze applied with an electrostatic charge, is added after firing then refired to a much lower cone, often cone 2. Any gilding or colored enamels are then applied and the china is refired again to cone 016 or so. <strong>The total glaze weight will add only 5% to the total weight</strong>.</p>
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<p>In contast, for fun I made a large and very thick fountain (about 14 to 18 mm thick) with a very porous clay with a lot of grog, Laguna Big Pot. After being bisqued this porous clay absorbed so much glaze to become water-proof that the glazed and fired fountain weighed as much as the original wet clay used to build it.</p>
<p>This fountain weighed as much as the original wet clay (about 41 kilos) because the porous bisqued clay took on 50% of its weight in glazes. It sits in our studio as a "white elephant".</p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/3127179731?profile=original" target="_self"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/3127179731?profile=RESIZE_1024x1024" class="align-left" width="721"/></a></p>
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<p>Top view showing how thick the piece is and the drip-irrigation plumbing of the fountain.</p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/1606560835?profile=original" target="_self"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/1606560835?profile=RESIZE_1024x1024" class="align-left" width="721"/></a></p>