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PeterH

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  1. After the informed comments ... If you cannot fire it, then clay probably isn't the right material for the finished product. Just the indicate that there are other options. It's costly, but you could model it in clay, make a flexible mould, and construct the final object with some cold-cure material. As was done with these: Here is Garfield table made out of concrete: https://www.architecturaldigest.com/story/ava-nirui-splurged-on-a-cartoon-coffee-table-and-regrets-nothing And a waste-mould way of casting large concrete sculptures And there are concretes designed for a degree of moulding, although your strength might be an issue for your project.
  2. You might also try hot water: Sodium Silicates: Versatile Inorganic Adhesives https://tinyurl.com/e2zvdaee Cleanup with water. When allowed to harden, silicates may need hot water to remove.
  3. Wrong question. The chart is purely about what happens to the channels in the sepiolite crystal structure. The authors wanted to remove "the 2nd molecule of coordinated water" without degrading the channel itself. I guess that the indigo just sits there during this process (but becomes eventually becomes slightly better attached to the wall of the channel as the water is no longer there). Even if indigo can stand these sorts of temperature in the protected environment of the channel is says nothing about its behaviour in other circumstances. BTW I'm relying on a several-years-old memory of the experimental to recreation of Maya Blue, which AFAICR was a wet (or wet then dry) process. Note however this quote from the earlier reference maya blue recipe https://www.nataliestopka.com/goingson/postid-6 Over the course of a few minutes, you will see the two powders combine and turn a uniform blue color. At 356 degrees Fahrenheit the indigo sublimates to a gas, bypassing the liquid phase, and is immediately absorbed by the clay. Remove the pot from heat and allow to cool. The color will have a violet tinge when hot, but turn turquoise as is cools. You now have Maya blue pigment, indigo locked inside and stabilized by the clay. ... although if you look up indigo in the same Chemical Book you used for Vat Blue 4 you get: - MP >300 °C(lit.) BP 405.51°C (rough estimate) ... and no mention of sublimation ... but then wiki gives: - MP 390 to 392 °C no BP as decomposes ... so I haven't a clue PS I've been thinking about the use of a photo-sensitive ester of indigo to achieve patterns in fabric, and cannot immediately see how the process can be applied to Maya Blue patterns. I assume that you wash-out the unexposed "leuco esters", and cannot see how a wash-out mechanism can be applied to a ceramic body.
  4. To illustrate @Callie Beller Diesel's point Techno File: Rare Earths at Cone 6 https://ceramicartsnetwork.org/ceramics-monthly/ceramic-supplies/ceramic-glazes-and-underglazes/techno-file-rare-earths-cone-6/# int Dichroic effects are somewhat rare in gemstones, but always elicit a smile when observed or held in a hand as the color change transpires. Neodymium is notorious for possessing dichroic properties in glass, such that the development of a dichroic glaze is not unreasonable. To explain dichroics, I should communicate that the glaze is not actually changing in any way; the quality of light striking the glaze is changing and we can note that by watching the color change in the dichroic glaze. Blue-heavy lights like CFL bulbs, fluorescent bulbs, or halogen street lamps are mostly on the blue side of the spectrum and will cause neodymium to appear a soft to vibrant blue. Incandescent sources and sodium street lamps produce light that is mostly on the red side of the spectrum, thus one would primarily see only a pink/red glaze from the light reflected back. Full-spectrum sources, like some LEDs and natural sunlight, simultaneously reflect back both red and blue colors, thus we see lavender. In (3), a single yunomi has been exposed to halogen, incandescent, and LED lights, showing the three color extremes for neodymium glazes.
  5. As @Callie Beller Diesel says if you can give us some idea what you are trying to do, we would be in a better position to contribute. PS 1) As to the what temperatures some indigo colours can survive. Recreating highly specialised indigo-based pigments can require temperatures in the range 300-550°C to form them. These pigments are based on the molecular-level encapsulation of "indigo" molecules in microscopic channels in a handful of clay-like materials, especially sepiolite & palygorskite. Real state-of-the-art nanotechnology, but the pre-Columbians got there first with "Maya Blue". Indigo chemisorption in sepiolite. Application to Maya blue formation https://www.sciencedirect.com/science/article/pii/S1631074806000373 Why 300-550°C? Above this temperature the sepiolite crystal structure degrades. These pigments can be made as a powder, or applied to ceramic objects (providing the sepiolite/palygorskit structure remains intact). 2) maya blue recipe https://www.nataliestopka.com/goingson/postid-6 3) I'm certain that it's best to get the sepiolite or whatever from a artist supplies outlet. Sepiolite forms the basis of some cat litters and small-animal "dust trays", but I'm pretty sure that its crystaline structure has been degraded/lost. Kremer look promising https://www.kremer-pigmente.com/en/shop/fillers-building-materials/58945-sepiolite-powder.html# 4) 'ware dust, we are in the world of fibrous minerals best kept out of the lungs. (Kremer's sepiolite claims to be asbestos-free.) 5) Nice page about the open-structure of these minerals Cookies, Palygorskite, and Maya Blue http://backreaction.blogspot.com/2008/03/cookies-palygorskite-and-maya-blue.html
  6. Most of the impressive mocha videos I've seen -- like this one -- seem to use a slip which stays wet for a very long time. Is this peoples practical experience? And how do you stop the slip from drying too quickly? PS Physicists call this viscous fingering (or more formally Saffman-Taylor instability). There seems strong evidence that changes to the rheology (viscosity, sheer thickening/thinning, etc) of the liquids can have major effects on the nature of the fingering, so additives may be important. Abstract of a paper Viscous fingering in complex fluids https://iopscience.iop.org/article/10.1088/0953-8984/12/8A/366/pdf More rambling background paper Controlling Viscous Fingering https://www.europhysicsnews.org/articles/epn/pdf/1999/03/epn19993003p77.pdf
  7. Just to reference @Min's point that slow-cooling can effect the characteristics of some glazes (arguably in a way that happened naturally in a previous generation's highly insulated cone 10 kilns).
  8. For their Lab Furnaces Nabatherm seem to recommend "smoothing" the ramp. http://data.dt-shop.com/fileadmin/media/ga/43073_ga_enu.pdf Maybe you could achieve a similar effect by adding an extra ramp?
  9. That's your choice. but let's not let the discussion on terminology obscure MMR's point.
  10. ^^^^ slump mould (clay on concave face)........^^^^ hump mould (clay on convex face)
  11. Am I right in thinking that you want to make a mold for a mug-with-handle? If so you may find this thread of interest ... PS I find visuals helpful ... 2 & 3 piece molds for mug with handle 2-piece mold for handle combined 2-piece mold for handle-less-mug & handle "sprig" press-mold for proto-handles simple shapes can be cast in a 1-piece drop-out mold, which doesn't leave seams to be smoothed
  12. @PrateekThis reminded me of your angular bowls, passed on without evaluation. http://andrea-ceramics.blogspot.com/2015/05/tutorial-making-paper-plaster-mould.html
  13. >So the Bailey 25 pugmill/mixer is on my wish list, but I haven't been able to find any videos of its use as a mixer - Is this the right pugmill/mixer? The Bailey MSV-25 Mixer-Pugmill is put through the "ultimate blend challenge", by directly pugging equal amounts of white and dark clay directly through the machine to test for blending efficiency. The finished pugs are then sliced apart lengthwise to examine the final results. >Everywhere says "mixes in a few minutes" - well on a geological scale, several days is probably a few minutes At 4:58 it claims "237 lbs of clay in only 15 mins". I'll leave others to qualify that statement.
  14. Picture of Roman-era Terra Sig, it's a really thin layer of slip. 20μm ~ 0.0008 inches
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