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Tyler Miller

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  1. I seem to have stepped into something unintentional. I said two things in my initial comment. 1) There is a legal aspect of this that should be discussed with the proper experts 2) There is a ceramic aspect, which, given the conditions of the OP, is terracotta. I also said flameware bodies are superior in certain applications. The reasoning for my comment was the cost of research and development of a flameware body for personal use is disproportionate to its benefit. I would argue that the proper development of a flameware body for market is cost prohibitive for reasons related to the leg
  2. Bill, I took the time to find the context of the article you posted there. I'm not sure it's saying what you're thinking it does? Full article you excerpted is here: https://maxwellsci.com/print/rjees/v3-541-545.pdf Health Canada's maximum acceptable concentration for arsenic in drinking water is "10 ppm" this can be expressed as 10 μg/g (see link here https://www.healthlinkbc.ca/healthlinkbc-files/arsenic-drinking-water). 10 micrograms per gram is the maximum concentration allowed to be contained in drinking water. The article expresses that the average As content of the ear
  3. The website is health washing. Re: lead cadmium and barium (and arsenic! mentioned on the website). As long as your clay isn't coming from an industrial waste dump, it's a non issue? Cadmium that doesn't come from ceramics really only comes from industrial waste (google "itai-itai disease"). I'm pretty sure arsenic salts as a general rule sublimate out before earthenware matures (google that, though). I'm also pretty sure that any chemically significant amount of lead in a clay body (significant enough to cause toxicity issues) would have undesirable effects as a body flux on the cl
  4. There are two issues at work here. One ceramic, one legal. The legal aspect, is jurisdictionally related and is best left to the OP to figure out in their jurisdiction. Legal advice from legal experts, ceramics advice from ceramists. Mmkay? Good. The second question is re: non toxic cookware body. Terracotta, as has been mentioned, has been considered the standard cookware the world over for millenia across all human cultures. Firing low (like cone 017), sealing with oil, and using a heat diffuser on the stovetop are all you need. There are other flameware bodies (which are better
  5. https://en.m.wikipedia.org/wiki/Green_liquor It’s prolly this. All the necessaries are in the ash and iron is more likely a metallic contaminant than copper—occurring in an abundance orders of magnitude greater than Cu. This paper maybe helpful: https://www.nrcresearchpress.com/doi/pdfplus/10.1139/v78-462 (edited to make functional link) Kind regards, TM
  6. You’re missing flux. While I wouldn’t put too much weight on this comparison, the rice straw ash probably has more in common with the feldspar than it does with washed mixed hardwood ash.
  7. Wood ash is generally a source of flux, unwashed woodash a mixed of soluble potash and soda ash, washed woodash is mostly calcium carbonate. There is generally very little silica (with exceptions). Rice straw ash is high in silica (over 50% I think), like bamboo ash and other grasses—wheat straw ash can be silica rich too. Rice hull ash is almost entirely silica.
  8. Neil, I realize you addressed your comment to glazenerd. That said, if the sample isn’t ball clay or terracotta, the analysis coild be kaolinitic soil or something like it—something not too common in North America, but very common in tropical countries. Kaolin, organic matter, and maybe some silica sand, which tends to hang with kaolinite. 18% LOI—assuming complete analysis.
  9. Not as is. Is this a raw, as dug, product? The iron content will make a cosmetically unacceptable tile.
  10. Try to trim like the first three examples (badly drawn—my hands are a little cooked today), so that you’ve got the same thickness throughout the same pot. The foot ring shouldn’t create any thick spots where it joins the rest of the pot. The two X’d out show examples of pot bottoms that are likely to cause problems, either in drying, firing, or as weak points in use. They’re supposed to represent a bowl with an outer contour that doesn’t match the inner (bottom bowl) and a bowl with an extra thick ring around the base (middle right), which will cause a whole constellation of problems fo
  11. Bill, I’m sorry, I’m afraid I’ve given you the wrong impression. To clarify, cristobalite inversion is mostly done by 200C (392 F), and is traditionally considered to happened between 210 and 250 C (410-480 F) which is hotter than the above quoted 300 F (150ish C) by Neil et al. Sorry again for the confusion. I just wanted to frame a temperature in terms of what’s going on in the clay body/kiln, since that’s what matters. A temperature is just an arbitrary number until the mechanics of why it matters are there—and i feel like the OP deserves that kind of answer—at what temp and w
  12. I sortof thought it fell under the category of pyroplastic deformation, but creep might be an interesting way to look at it? I don’t know how useful those chapters will be in answering that, honestly. The reason I recommended it is that it talks about what the author calls “scatter of mechanical properties,” which is essential to understanding the behaviour of ceramic, in addition to the chapters “Fracture mechanics” and “Determination of Strength.” There are a lot of books that seem to be called “Mechanical properties of Ceramics,” but one with a more general chaper on deformatio
  13. Solid bibliography, LT! Looks like there’s a newer edition of the book I recommended in there. I’ll confess I probably got the original citation from a course biblio like that. A habit I’ve gotten into for research is to assemble a file to cut and paste citations into for later ref. Journal articles cite books or other articles I can’t read at the time, but feel might be useful, so i copy and paste the citations into a file. You end up getting a solid bibliography on a topic pretty quick. Sometimes a mailing list is a help for new stuff, if you can get on a publication review m
  14. This book might be useful in this discussion: Munz, D., Fett, T.: Ceramics, Mechanical Properties, Failure Behaviour, Materials Selection, Springer, 1999. From the dust jacket: Ceramic materials are widely used as components in a great variety of applications. They are attractive due to their good high temperature strength, high wear resistance, good corrosion restistance and other special physical properties. Their major drawback is their brittleness and the large scatter of mechanical properties. This book describes failure phenomena in ceramic materials under mechanica
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