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PeterH

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  1. Just for the record Ceramic Arts Daily publish "15 tried and true glaze recipes" for (at least) raku, cone 6 & cone 10. https://ceramicartsnetwork.org/docs/default-source/uploadedfiles/wp-content/uploads/2015/08/15rakuglazes.pdf https://ceramicartsnetwork.org/freebies/guide/15-tried-and-true-cone-6-glaze-recipes https://ceramicartsnetwork.org/freebies/guide/15-tried-and-true-cone-10-glaze-recipes
  2. @Chilly did you have any undercuts?... PS Comparing fondant moulding with press moulding (probably the the closest pottery equivalent) ... The fondant process: — uses a flexible non-absorbent mould — the fondant sets hard (without shrinking?) — the set fondant doesn't adhere strongly to the mould? — fondant sets strongly enough that peeling the flexible mould off undercuts doesn't damage them The press moulding process: — uses a rigid and absorbent mould — the clay shrinks and becomes harder as it dries — minimal drying time needed/required —— the mould absorbs water from the clay; so no air-drying needed and clay-mould adhesion is minimised —— if the clay dries too much it will shrink-on any texture in the mould — you cannot cleanly extract the (still fairly soft) casting if there are any undercuts. So I suspect that you could have issues with — air-drying the clay — getting the clay firm enough — clay shrinkage — clay-mould adhesion — the undercuts PS Using paper-clay would probably strengthen the clay and speed air drying to some extent.
  3. An relevance? https://www.lickinflames.com/obvara_june_2021.html Generally speaking, the hotter the pot going into the mixture, the darker it will be. Nearly glossy black pots are from the hotter side of the firing range and tan pots are usually from the cooler side of the range. Really hot pots held in the mixture longer will yield fewer patterns. Cooler pots held in the mixture longer will possibly not carbonize as they cool below the threshold where carbonizing can take place.
  4. Yes, but it may introduce more problems than it solves. To my untutored eye it looks like firing with a sitter would probably solve your slumping issues. ... but would introduce glazing issues. The classic bone china solution uses a supported high-fire bisque and an unsupported lower-fire glaze, which creates its own problems. Bone China https://digitalfire.com/glossary/bone+china The process is completely different than what a potter would do: Bisque fire, glaze, high fire. Bone china is bisque fired to high fire and then glazed at a very low temperature. Since the porcelain has zero porosity, getting a glaze to stick and dry on it is not easy, the process needed goes well beyond what a normal potter would be willing to do. PS Balancing slumping and decoration has a long history. Robert Tichane expressed his surprise when he finally realised that the ancient Chinese cup he regularly drank from had a guilded rim to disguise the lack of glaze on the rim (a result of firing the cup rim-down to minimise slumping). I'm having difficulty visualising your "handmade leather molds". I assume that they are semi-flexible press-moulds, but am unsure how you extract the bowl from the mould.
  5. What cone/temperature do you fire to? PS I'm a little confused about the small print in the kiln spec. Continuously working time on 1240 C (2264): 10 minutes ... and in the manual https://www.technicalsupermarket.com/(EN) RH-16L KILN INSTRUCTION MANUAL.pdf Using this kiln at temperatures higher than 1,240°C/2,264°F or for longer than 20 minutes at these temperatures may cause problems with heating element(s) and/or with the kiln’s metal body that are NOT under warranty.
  6. Sorry, came up with a complete blank under that name. BTW I believe that chick grit is finer than chicken grit, for example: https://www.legbarsofbroadway.co.uk/grit-soluble-insoluble/
  7. Pure speculation ... If you continue having problems -- I wonder if the t-sig might be the issue, for example - by not adhering to the resist slip sufficiently - by not adhering to the body sufficiently (any signs of t-sig on the AWOL slip?) Obviously it works well for the Riggs, as can be seen in Terra Sigillata 101: How to Make, Apply, and Troubleshoot Terra Sig https://ceramicartsnetwork.org/daily/article/Terra-Sigillata-101-How-to-Make-Apply-and-Troubleshoot-Terra-Sig Naked Raku Orb by Charles and Linda Riggs, 2003. 7 in. (18 cm) in width. Stoneware painted with white terra sigillata and polished with a soft cloth, bisque fired to cone 010, covered in resist slip and glaze. Sgraffito through glaze before raku firing to 1400ºF (760°C). ... but do any of the t-sig troubleshooting ideas in the article apply?
  8. >>>> Please ignore, I thought I had deleted this FACTUALLY INCORRECT post <<<
  9. On very little evidence this might be a grass-ash (rather than a wood-ash). South Okanagan Grasslands Protected Area https://bcparks.ca/south-okanagan-grasslands-protected-area/ The Richter Pass has long been a priority for conservation efforts in the Okanagan. The primary role of the South Okanagan Grasslands Protected Area is to protect the dry grasslands and open forests that represent one of the four most endangered ecosystems in Canada. Glazy has some lawn-ash analyses at https://glazy.org/materials/15037 The materials section at glazy might complement digitalfire's coverage https://glazy.org/materials?primitive=1 Digitalfire also has Those Unlabelled Bags and Buckets https://digitalfire.com/article/those+unlabelled+bags+and+buckets
  10. Yes. Of course you are going to have a seam in the middle of the handle which may leave some sort of casting mark in the handles which you will need to make-good. PS Interesting but of low relevance: a thread that started out with a question on cast handles and digressed big-time.
  11. I think that you will find this difficult. It's more usual to use some sort of clay "build-up" to keep the plaster under control, as in PS A handle is nice and thin so there is no difficulty using a solid clay build-up. For larger objects you may want to minimise the amount of clay used for the build-up. e.g. https://youtu.be/pXQgi6vW22I?t=698 To state the obvious: bits of plaster can explode in the kiln, so keep any clay used for mould-making well away from the clay you use for making pots.
  12. There is a half-way house you might consider. Using a digital meter on a disconnected kiln. Measuring the resistance between connectors 2 & 6 on the relays before and after your changes would have clearly indicated a wiring problem while the kiln was still open. Probably before you had started rewiring the second element pair. The measurement could also give and indication of when the elements need replacing. Ideally you would like to know the resistance of each element, but that would require breaking & remaking the connections.
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