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mrcasey

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About mrcasey

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    Advanced Member

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  • Location
    WV
  • Interests
    As far as ceramics go, I'm interested almost exclusively in hand building slab pots for bonsai. I'm looking to create traditional forms with very simple geometries.

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  1. I understand that the thermal expansion of the glaze being greater than that of the clay body results in crazing, but I'd like to be able to give my students a visual model for what's going on. What do you guys think about the analogy of a hot bowling ball with mud on it. As the bowling ball cools, it will shrink just a little; as the mud dries, it will shrink a lot. The mud will try to shrink down but pull away in some places creating little cracks. I realize the analogy doesn't quite work because the mud is shrinking because evaporation and not cooling. What do you guys think?
  2. A few of my friends in our community studio have purchased small containers of "flux". The flux is meant to be brushed over or under the glaze. I'm the glaze maker and a few people approached me about making our own. It's cone 6 stuff and I just figured it was probably water, frit 3134 (or something similar), and a little bit of clay. Has anyone experimented with this stuff and/or made up their own recipe?
  3. I suspect that this stuff was never actually used in our studio. I further suspect that it was taken from a local community college's larders when their ceramic art program was shut down.
  4. I recently found an old abandoned box of standard overglazes in our studio closet. We only fire to cone 05 and 6 electric. My understanding is that these overglazes are applied after the glaze firing and then fired to a very low temperature. The info on the containers is kind of vague about cone temperature and application. The digital fire pages says that some overglazes or onglazes are fluxed with bismuth and will melt at around 1300F! Maybe I could use them in pit firing? Can anybody tell me a little more about these "overglazes" and how/why someone might want to use them.
  5. I've spent the entirety of my time as a potter using various cone 6 stoneware. In our studio, we have access to a white body (Laguna #65). What is the advantage, if any, to switching to a cone 6 porcelain?
  6. The only reason to cover the pot is to keep unsafe volatile material out of the liner glaze.
  7. Suppose that I throw a raku clay pot, put a liner glaze in it, and fire to cone 6 electric. Suppose that I then put a clay cover over the pot rim and pit fire it. Would that give me a food safe vessel? What if I just used regular food safe cone 6 clay?
  8. What is a good definition of centered clay? (I'm especially curious about Tyler's and Baymore's opinions) (1) What is the mathematical/physical definition of a centered piece of clay? and (2) Why does coning up and down center a piece of clay?
  9. A member of our community studio would like to mix up a batch of Patsy Green 2 from John Britt's mid fire book. The lithium concerns me as does the 4% copper. I don't have glaze software to look at the limits and I was wondering if somebody could run the numbers for me. Also, I'd be interested in anyone's opinion about the safety of the glaze. Neph Sy 44 Silica 18.9 Whiting 7.9 Kaolin 2.3 Dolomite 5.6 Gerstley Borate 12.8 Lithium Carbonate 4.8 Zinc Oxide 3.8 ------------------------------- Copper Carbonate 4 Bentonite 2
  10. Isn't this backwards? If the glaze hard layers on the bottom, it needs flocculated.
  11. I have no plans to mix up another batch of this stuff. I'd just like to fix this one as best I can and move on...
  12. If I had it to do over again, I'd calcine 1/2 the kaolin and not add bentonite. I certainly wouldn't use this new sodium bentonite that makes gelfromhell. The reason I added the bentonite is because it says to in Britt's recipe. John Britt's 3M-4 Matte with 5% gray mason stain Custer Feldspar 6 % Silica 8 % Wollastonite 20 % Kaolin 40 % Frit 3134 12 % Talc 14 % : 100% Mouse Gray M. Stain 5% Bentonite 2 % The first s.g. measure was 1.5 which was crazy thick. It looked fine on a test tile but gave some of the other studio members some serious crawling issues. People asked that I thin it out. So I did. It crawled again, so I thinned it some more. I just kept adding water until I got down to an amazingly low s.g. of 1.25. At 1.25, the stuff is the thickness of heavy cream and still crawls. On top of all that, it flows a bit too much and becomes streaky. My new plan is to actually take some water out and then deflocculate with darvan 7. If that doesn't work, I'm stumped. I'm a little annoyed that my little 2" X 3" test tile didn't reveal any problems. TEST TILES SUCK!
  13. When a glaze is really thick, how does one know whether it needs more water or needs to be deflocculated?
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