Glazes - Theory and Chemistry - Electric Mid&Hi Fired Ceramics2024-03-29T08:14:19Zhttps://cone6pots.ning.com/forum/categories/glazes-theory-and-chemistry/listForCategory?feed=yes&xn_auth=noColemanite and spodumene in glazestag:cone6pots.ning.com,2021-02-26:2103784:Topic:1702112021-02-26T18:19:58.495ZLucahttps://cone6pots.ning.com/profile/Luca
<p>Hallo,</p>
<p>Is there anyone who can give me some advice on using colemanite and spodumene in glazes?</p>
<p>I have read that use of colemanite can cause some problem in glaze if colemanite is present in big concentration (decrepitation). What can be the maximum<span> </span>concentration that give not big problems? 10%?</p>
<p>If my firing is slow is it possible that this problem will be less?</p>
<p>About spodumene: I have seen that can be better to wash it and that big concentration…</p>
<p>Hallo,</p>
<p>Is there anyone who can give me some advice on using colemanite and spodumene in glazes?</p>
<p>I have read that use of colemanite can cause some problem in glaze if colemanite is present in big concentration (decrepitation). What can be the maximum<span> </span>concentration that give not big problems? 10%?</p>
<p>If my firing is slow is it possible that this problem will be less?</p>
<p>About spodumene: I have seen that can be better to wash it and that big concentration can determine some "wave" In the glaze. Is this problem bigger in single firing? Someone know why it is better to wash spodumene?</p>
<p>Many thanks</p>
<p>Luca</p> Wood ash from pellet stovetag:cone6pots.ning.com,2021-02-21:2103784:Topic:1701012021-02-21T15:27:36.918ZLucahttps://cone6pots.ning.com/profile/Luca
<p dir="ltr">Is there anyone who uses the ash produced by pellet stoves and has experience on its use?<br></br> I'm wondering if there are any problems using this ash: I got the impression that the ash is coarser than the fireplace ash.<br></br> Actually the real difference is perhaps that the ash from the pellet stove is fine and fairly homogeneous but has few very thin particles: it seems fine, because there are not big pieces of coal but perhaps the really thin particles are missing because of the…</p>
<p dir="ltr">Is there anyone who uses the ash produced by pellet stoves and has experience on its use?<br/> I'm wondering if there are any problems using this ash: I got the impression that the ash is coarser than the fireplace ash.<br/> Actually the real difference is perhaps that the ash from the pellet stove is fine and fairly homogeneous but has few very thin particles: it seems fine, because there are not big pieces of coal but perhaps the really thin particles are missing because of the forced stove ventilation. Once washed, the ash from the pellet stove is more difficult to filter and remains darker, sometimes almost black. </p>
<p dir="ltr">Is it possible that this aspect gives problems? Can it be solved in your opinion with some adjustments on the stove?</p>
<p dir="ltr"></p>
<p dir="ltr">First photo is wood ash from fireplace</p>
<p dir="ltr">Second photo is from pellet stove</p>
<p dir="ltr">The red and blue effect in the photos is a camera fault.</p>
<p dir="ltr"><a href="https://storage.ning.com/topology/rest/1.0/file/get/8581258466?profile=original" target="_blank" rel="noopener"><img src="https://storage.ning.com/topology/rest/1.0/file/get/8581258466?profile=RESIZE_710x" class="align-full"/></a><a href="https://storage.ning.com/topology/rest/1.0/file/get/8581261456?profile=original" target="_blank" rel="noopener"><img src="https://storage.ning.com/topology/rest/1.0/file/get/8581261456?profile=RESIZE_710x" class="align-full"/></a></p> 5 to 10 years in the bucket and its not the same.tag:cone6pots.ning.com,2019-03-15:2103784:Topic:1523952019-03-15T20:26:57.602ZOtto Wengerhttps://cone6pots.ning.com/profile/OttoWenger756
<p></p>
<p></p>
<p>5-10 years ago I mixed up a bucket of Pete Pinnell's Weathered Bronze Green cone 6-7. It was fine years ago and produced just the look I wanted. This time the results were not good. The glaze is very matt and is Dark gray only. No green at all. I first suspected it may have been that I needed to be at cone 7 down rather than cone six down. As you can see in the photo re-firing to cone 7 has not solved the problem. I'm now feeling that there has been a chemical change over…</p>
<p></p>
<p></p>
<p>5-10 years ago I mixed up a bucket of Pete Pinnell's Weathered Bronze Green cone 6-7. It was fine years ago and produced just the look I wanted. This time the results were not good. The glaze is very matt and is Dark gray only. No green at all. I first suspected it may have been that I needed to be at cone 7 down rather than cone six down. As you can see in the photo re-firing to cone 7 has not solved the problem. I'm now feeling that there has been a chemical change over the 5-10 year period. I can of course just mix up a new batch but then I would still not know what happened to the first old batch. I'd love to know why! Any educated guesses would be appreciated.</p>
<p></p>
<p>Recipe Name: <span> </span><strong>Pete's Weathered Bronze</strong></p>
<p>Cone: 6-9 Color: green bronze<br/>Firing: Oxidation Surface: Matte</p>
<p>Amount Ingredient<br/>60 Nepheline Syenite<br/>20 Strontium Carbonate<br/>1 Lithium Carbonate<br/>10 Ball Clay--Old Mine #4<br/>9 Silica</p>
<p>100 Total</p>
<p> Additives<br/>5 Copper Carbonate<br/>5 Titanium Dioxide</p>
<p></p>
<p>Thanks</p>
<p>Otto Wenger<a href="https://storage.ning.com/topology/rest/1.0/file/get/1439183076?profile=original" target="_blank" rel="noopener"><img src="https://storage.ning.com/topology/rest/1.0/file/get/1439183076?profile=RESIZE_710x" class="align-full"/></a> </p> Online Glaze Calculation and Theorytag:cone6pots.ning.com,2018-05-19:2103784:Topic:1489462018-05-19T19:10:06.603ZGeorge Lewterhttps://cone6pots.ning.com/profile/GeorgeLewter
<p>Max Katz of Alfred University runs interactive 3 month classes in his understanding glaze materials workshop. You can watch some of his videos on YouTube and get a sense of his teaching style and and level of expertise. Sample this video to see the depth of the materials. <a href="https://www.youtube.com/watch?v=HyLjAg1_8_4" rel="noopener" target="_blank">https://www.youtube.com/watch?v=HyLjAg1_8_4</a></p>
<p>The 14 lectures from the class are available on a stand-a-lone basis for $300…</p>
<p>Max Katz of Alfred University runs interactive 3 month classes in his understanding glaze materials workshop. You can watch some of his videos on YouTube and get a sense of his teaching style and and level of expertise. Sample this video to see the depth of the materials. <a href="https://www.youtube.com/watch?v=HyLjAg1_8_4" target="_blank" rel="noopener">https://www.youtube.com/watch?v=HyLjAg1_8_4</a></p>
<p>The 14 lectures from the class are available on a stand-a-lone basis for $300 US</p>
<p>An organized class with all the following (with classes starting in July and Oct. of 2018:</p>
<ul>
<li>$500 for the full experience.</li>
<li>We will have 14, hour and a half to two hour on-demand lectures, <strong>LIVE</strong> bi-weekly online discussions, Q&A with Matt and Rose, Readings, and Experiments</li>
<li>You will receive copies of our lectures notes!</li>
<li>Registration is open now and is LIMITED! Reserve your spot now!</li>
<li>The next session will begin October 1st</li>
<li><a href="https://app.ruzuku.com/courses/27655/about" target="_blank" rel="noopener">Sign Up HERE for the JULY<span> </span></a></li>
<li><a href="https://app.ruzuku.com/courses/27782/enroll" target="_blank" rel="noopener">Sign Up HERE for October </a></li>
</ul>
<p>Here is the website home page: <a href="https://www.ceramicmaterialsworkshop.com/" target="_blank" rel="noopener">https://www.ceramicmaterialsworkshop.com/</a></p> Raw glaze recipetag:cone6pots.ning.com,2018-03-16:2103784:Topic:1481972018-03-16T22:39:36.097ZTom Humphrieshttps://cone6pots.ning.com/profile/TomHumphries
<p>Hi,</p>
<p>I've been trying to work out a raw glaze recipe, after reading a few books suggesting ball clay works better for raw glazing leather hard pots. This glaze is intended to fire to ^8 and will be in an electric kiln, although perhaps gas firing in the future. I'm planning to make up a kg or so to test. Just wondering if anything sticks out as problematic to anyone? It is withing the green and copper limits for this cone range, and expansion seems ok according to a glaze simulator I…</p>
<p>Hi,</p>
<p>I've been trying to work out a raw glaze recipe, after reading a few books suggesting ball clay works better for raw glazing leather hard pots. This glaze is intended to fire to ^8 and will be in an electric kiln, although perhaps gas firing in the future. I'm planning to make up a kg or so to test. Just wondering if anything sticks out as problematic to anyone? It is withing the green and copper limits for this cone range, and expansion seems ok according to a glaze simulator I used. </p>
<p>Thanks! </p>
<p>Tom</p>
<table id="tblRecipe" border="0">
<tbody><tr><th colspan="4" align="center">BallClay2</th>
</tr>
<tr><td class="m">HP 71 Ball Clay</td>
<td>32.00</td>
</tr>
<tr><td class="m">BPS Soda Feldspar</td>
<td>32.00</td>
</tr>
<tr><td class="m">Quartz</td>
<td>14.00</td>
</tr>
<tr><td class="m">Wollastonite</td>
<td>12.00</td>
</tr>
<tr><td class="m">BPS Calcium Borate Frit</td>
<td>10.00</td>
</tr>
</tbody>
</table>
<p></p> Light Rutile Substitutetag:cone6pots.ning.com,2017-01-09:2103784:Topic:1398582017-01-09T21:21:01.737ZGeorge Lewterhttps://cone6pots.ning.com/profile/GeorgeLewter
Has anyone reformulated dark rutile with titanium dioxide and/or other compounds to closely approximate light rutile? The light type had asbestos in its makeup, which is why it is no longer available. The dark version is darkening glazes like Nutmeg far more than previously.
Has anyone reformulated dark rutile with titanium dioxide and/or other compounds to closely approximate light rutile? The light type had asbestos in its makeup, which is why it is no longer available. The dark version is darkening glazes like Nutmeg far more than previously. Soda firingtag:cone6pots.ning.com,2016-11-13:2103784:Topic:1384782016-11-13T16:44:27.877ZAyjayhttps://cone6pots.ning.com/profile/AlexanderJohnPleasance
<p>I know I can't Soda fire in my electric kiln (without ruining it) but is there a simple way to fake a Soda glaze?</p>
<p></p>
<p>I plan to test a couple of ideas but wondered if anyone had beat me to it.</p>
<p></p>
<p>First idea is to make a saturated solution of Sodium Carbonate and either spray/dip/paint it on a bisqued piece and just fire it (on a catch plate).</p>
<p></p>
<p>I'll try a second pot with a (hopefully) complimentary glaze on it as well, and maybe a third with the Soda…</p>
<p>I know I can't Soda fire in my electric kiln (without ruining it) but is there a simple way to fake a Soda glaze?</p>
<p></p>
<p>I plan to test a couple of ideas but wondered if anyone had beat me to it.</p>
<p></p>
<p>First idea is to make a saturated solution of Sodium Carbonate and either spray/dip/paint it on a bisqued piece and just fire it (on a catch plate).</p>
<p></p>
<p>I'll try a second pot with a (hopefully) complimentary glaze on it as well, and maybe a third with the Soda sprayed on afterwards.</p>
<p></p>
<p></p>
<p></p>
<p></p> Naragon White Glaze- Accidental Recipe Modificationtag:cone6pots.ning.com,2016-10-09:2103784:Topic:1376052016-10-09T16:36:41.800ZRosemary Davishttps://cone6pots.ning.com/profile/RosemaryDavis
<p>I'm going to just open this thread with a disclaimer. Drinking wine and glaze mixing at the same time do not make good bed fellows. Be that as it may, I mixed-up a test batch of Naragon White and failed to add the Zircopax & Bentonite. Because that was such a good decision, I then proceeded to glaze all of my bowls with a layer of Pseudo Naragon White, ALL OF THEM. Despite my repeated stupidity, the Kiln God was uncharacteristically merciful. When I took my bowls out of the kiln,…</p>
<p>I'm going to just open this thread with a disclaimer. Drinking wine and glaze mixing at the same time do not make good bed fellows. Be that as it may, I mixed-up a test batch of Naragon White and failed to add the Zircopax & Bentonite. Because that was such a good decision, I then proceeded to glaze all of my bowls with a layer of Pseudo Naragon White, ALL OF THEM. Despite my repeated stupidity, the Kiln God was uncharacteristically merciful. When I took my bowls out of the kiln, sitting on top of the iron red was a subtle light blue. There was no crazing or bubbling and I really like the color. My question to you is food safety and why it was blue? You see, I've been eating off of them, and I'd prefer not to do anymore brain damage...</p>
<p></p>
<p><strong><span style="text-decoration: underline;">Naragon White Cone 6 Oxidation Glaze</span></strong></p>
<p></p>
<p>Dolomite 4%</p>
<p>Gertsley Borate 26%</p>
<p>Whiting 6%</p>
<p>F-4 Feldspar 31%</p>
<p>EPK Kaolin 8%</p>
<p>Silica (Flint) 25%</p>
<p><strong>Total</strong> 100%</p>
<p></p>
<p><strong>Add</strong>:</p>
<p>Zircopax 12%</p>
<p>Bentonite 2%</p>
<p></p>
<p></p>
<p></p> Recipes from John Britt's "The Complete Guide To Mid-Range Glazes", now in Insight-Livetag:cone6pots.ning.com,2015-09-17:2103784:Topic:1250642015-09-17T15:09:21.636ZLawrence Weathershttps://cone6pots.ning.com/profile/LawrenceRWeathersPhD
<p><span style="font-size: 14px; color: #222222; font-family: 'Helvetica Neue', Arial, Verdana, sans-serif;">John Britt has graciously allowed Tony Hansen, creator of Insight, to add the recipes from his book, "The Complete Guide To Mid-Range Glazes", into Inside-Live. </span></p>
<div><font color="#222222" face="Helvetica Neue, Arial, Verdana, sans-serif"><span style="font-size: 14px;"> …</span></font></div>
<p><span style="font-size: 14px; color: #222222; font-family: 'Helvetica Neue', Arial, Verdana, sans-serif;">John Britt has graciously allowed Tony Hansen, creator of Insight, to add the recipes from his book, "The Complete Guide To Mid-Range Glazes", into Inside-Live. </span></p>
<div><font color="#222222" face="Helvetica Neue, Arial, Verdana, sans-serif"><span style="font-size: 14px;"> </span></font></div>
<div><font color="#222222" face="Helvetica Neue, Arial, Verdana, sans-serif"><span style="font-size: 14px;">It is still important to buy John's book because it offers far more than just glaze recipes. It's an outstanding book that provides a wealth knowledge about glaze chemistry.</span></font></div> Predicted COE (Coefficient of Expansion) - trust your actual results rather than the predicted COEtag:cone6pots.ning.com,2015-09-08:2103784:Topic:1247392015-09-08T22:34:00.712ZNorm Stuarthttps://cone6pots.ning.com/profile/NormStuart
<p>One of the helpful tips Tony Hansen of Digitalfire has passed on to me is the "calculated thermal coefficient of expansion" in Insight-Live and other glaze software is not very accurate when used to predict the COE of a clay body.</p>
<p></p>
<p>We know the COE predictions for clay are often wrong because it's very easy to measure the COE of a fired clay in a <strong>dilatometer, shown below as a photo and a diagram</strong>.</p>
<p></p>
<p>Our supplier, Laguna Clay, provides the actual…</p>
<p>One of the helpful tips Tony Hansen of Digitalfire has passed on to me is the "calculated thermal coefficient of expansion" in Insight-Live and other glaze software is not very accurate when used to predict the COE of a clay body.</p>
<p></p>
<p>We know the COE predictions for clay are often wrong because it's very easy to measure the COE of a fired clay in a <strong>dilatometer, shown below as a photo and a diagram</strong>.</p>
<p></p>
<p>Our supplier, Laguna Clay, provides the actual tested COE and other specs for most of their clays. - <a href="http://www.lagunaclay.com/clays/western/wc861.php">http://www.lagunaclay.com/clays/western/wc861.php</a></p>
<p></p>
<p>Actual tested COE was an important piece of information when making a "flameware" clay body requiring very low expansion because small changes, like tap water instead of distilled water, make significant and undesirable changes in the actual COE of the fired clay body. These large changes in the COE of the flameware clay body are not at all predicted by Insight and other glaze software.</p>
<p></p>
<p><img alt="http://www.azom.com/images/equipments/EquipmentImage_214.jpg" src="http://www.azom.com/images/equipments/EquipmentImage_214.jpg"/><img alt="http://www.ceramicindustry.com/ext/resources/Issues/June2012/CI0612-ta-slide1-615px.jpg" src="http://www.ceramicindustry.com/ext/resources/Issues/June2012/CI0612-ta-slide1-615px.jpg"/></p>
<p></p>
<p>This always left me curious why the predicted COE for clay would often be inaccurate, but the predicted COE for glaze would be correct.</p>
<p></p>
<p><strong>I've come to realize that the same math models are also probably not always accurate when predicting the C.O.E. of glaze as well. </strong>Definitely something to bear in mind.</p>
<p></p>
<p>One example is Boron which is both a flux, and a glass former like silica. Ceramic research papers show can allow a glaze to fit clay bodies with a much wider range of COE than you might expect by creating a variety of different structures depending on the force and movement while the glaze is cooling. Boron can also expand the temperature range of structural stability for vitrified porcelain.</p>
<p><a href="http://digitalfire.com/4sight/library/reducing_the_firing_temperature_of_a_glaze_from_cone_10_to_6_44.html" target="_blank">Digitalfire - Adjusting a Cone 10 recipe to Cone 6</a></p>
<p><a href="http://www.borax.com/docs/euf_pdfs/euf-borates-boratesinglazesandenamels">http://www.borax.com/docs/euf_pdfs/euf-borates-boratesinglazesandenamels</a></p>
<p></p>
<p>A practical example of this is <strong>Zam Celadon ^6</strong>, a glaze fluxed primarily with Nepheline Syenite which contains 9.8% Na2O and 4.6% K2O creating a relatively high COE of 7.4, very often resulting in crazing.</p>
<p></p>
<p>This is terrific if you want to achieve this <strong>crackle look</strong> of a crazed glaze which makes it unsuitable for functional use. This glaze will even crackle when applied to Laguna Clay Frost WC-437 which has a measured body COE of 6.99 which is fairly high for clay. Most would think a glaze with a COE of 7.4 over a clay with a COE of 6.99 should be a good fit, but not in practice.</p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/3036818689?profile=original"><img class="align-left" src="http://storage.ning.com/topology/rest/1.0/file/get/3036818689?profile=original" width="360"/></a></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p>This glaze contains Ferro Frit 3124, which is relatively low in Boron Oxide (B2O3) - only 13.74%.</p>
<p></p>
<p>If I replace the Ferro Frit 3124 with Ferro Frit 3195 (a balanced low-fire clear having 22.62% Boron Oxide), <strong>the percentage of Boron Oxide B2O3 increases by 82% from 0.17 to 0.31</strong> but very little else of the glaze chemistry is changed.</p>
<p></p>
<p>The <strong>predicted COE</strong> declines a tiny amount from 7.4 to 7.2 but all crazing ceases regardless of which clay body I've used it on. So the extra Boron Oxide provides additional fitting ability which is not captured in the predicted COE.</p>
<p></p>
<p>One drawback is a glaze with a high percentage of early melters, such a high boron oxide percentage, can be counter-productive if there are glaze ingredients which continue to off-gas above Cone 2, as the boron will likely have already melted the glaze by this temperature, which would lead to the glaze foaming, leaving it with pinholes if the melt is too viscous.</p>
<p></p>
<p><strong>Pete Pinnell</strong> has suggested that if we had relied exclusively on Glaze Limit Formulas we would be missing most of the interesting glazes which have been created over the last 50 years, and he a makes a pretty compelling case for that.</p>
<p></p>
<p>Pete's Weathered Bronze Green, which can be used at Cone 10 or Cone 6, with a predicted COE of 8.7 is just one of many examples. With a Silica to Alumina ratio of only 4.7 to 1, Weathered Bronze Green is more of an engobe rather than a glassy glaze.</p>
<p></p>
<p>Sometimes our biggest problems comes from the false things we "know" to be true rather than things we're pretty sure we don't know.</p>
<p></p>
<p>If you experience crazing or shivering, comparing the COE or the clay with the predicted COE of the glaze can help give you an idea of how to fix the problem, but test tiles will tell the real result of your adjustments rather than the predicted COE. Added Boron is just one of the ways to fix a COE mismatch. Cooling glaze more slowly can at least give the appearance that mismatch problems have been cured as no glaze defects will be visible after firing.</p>
<p></p>
<p>The logic used to predict COE is trying to accurately model often very complex ceramic structures</p>
<p>As ceramic researchers learn more, they way COE is predicted will almost certainly become more accurate as we learn to better model the real world. Currently test tiles are our best friend.</p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/3036818894?profile=original"><img width="750" class="align-left" src="http://storage.ning.com/topology/rest/1.0/file/get/3036818894?profile=RESIZE_1024x1024" width="750"/></a></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>