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glazenerd

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About glazenerd

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    Now & Then

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  • Location
    St. Louis, Mo.
  • Interests
    Crystalline glaze chemistry. Porcelain, Stoneware, Fritware, 04 Colored Porcelain clay research & formulation.
    Ceramics Monthly Articles: Jan. 2018 Cation Exchange (plasticity), April 2018 SSA Clay Formulation, May 2018 Bloating and Coring.
    Feb. 2019 Ceramics Monthly- Clay Body Shopping Guide
    March 2019 Ceramics Monthly - Porcelain 201
    June 2019 Ceramics Monthly Clay Restoration
    Sept. 2019 Clay Memory
    Oct. 2019 Firing Programs

    Email: optix52@aol.com

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  1. There are two methods: dry screening and wet slurry. If you collecting from a creek bed then you will get a range of material ranging from organis to large pebbles. The clay from a creek bed is typically very fined grained due to being sedimentary. Using a window screen to dry process is perfectly fine: then switch to 60 or 80 mesh to capture clay. Any particles larger than that would be rough on your hands anyway. You could dry screen through a window screen: then wet slurry what passes through the screen. Mix with plenty of water: mix with a drill/paddle or stir vigoursly by hand. Allow it to stand for 1-2 hours, then ladle off the water into a pillow case. Leave the sediment on the bottom, you are only capturing the suspended fine particles. All that said: collecting clay from a creek bed is not ideal because of all the Organics and large particles. Walk the creek and look for areas where sediments have collected in low spots or where there is little flowing waters. Sediments collect in these areas and your clay yield will be higher for the same amount of effort. Tom
  2. This article covers the stimulus package (USA) for individuals. It is formatted as FAQ, with corresponding answers. https://www.nytimes.com/article/coronavirus-stimulus-package-questions-answers.html
  3. Hi Mary: Thought you might be interested in seeing a hematite (iron) bearing clay. On the left is Red Art for reference, and on the right is hematite clay from OK. ( TY DA) it fires deep red at cone 6 J
  4. Hulk: Ball clay do more than just add plasticity. Clay basics: ball clay is a 2:1 particle which holds moisture on its inner platelets which extends drying time. Porcelain (kaolin) is a 1:1 particle ( no inner platelet) which holds moisture only on its surface which results in much shorter drying time. The higher the plasticity level of ball clay= the longer the drying time.
  5. Liam: jobs do not bring honor to the man: the man brings honor to the job.
  6. The Senate is getting ready to vote on a stimulus package for those effected by this virus. Includes direct payments to citizens, tax deferred payments, tax credits for small business, waiver for filing late: and a list of many other perks. I would expect to see detailed lists this weekend (March 20)- be watching for it.
  7. TY Min. A couple of Doctors in the States have said they do not work. However, States, Counties, and hospitals have been asking the public to bring these masks in if they have them. To my knowledge, the mask worn in hospitals are N95, unless they are using the full level 4 bio suits. Certainly some mixed messages State side.
  8. Like Roberta: my wife and I live on acreage- surrounded by more timber and farmland. Very thankful we do not live in a dense urban area. I retired from home building almost 2 years ago, I still do high end finish work for high end contractor friends. I work alone mostly, rarely deal with people face to face: and have work for several more months. I am fully aware of my fortunate situation: so my concerns are for others who will be hurt by the uncertainty of these times. My mother is 87; my brother has her for a month, then my sister for a month: then me. She will stay with one of us until this storm passes. On the bright side: many potters have masks or respirators if those needs arise.
  9. https://www.sba.gov/page/coronavirus-covid-19-small-business-guidance-loan-resources
  10. Standard 365 is a Grolleg porcelain C6 body: Grolleg is as pure as kaolin/clay comes- extremely low levels of titanium, iron, and magnesium: which at higher levels can produce natural color. The MDS states 30% feldspar and 15% Nep Sy ( sodium feldspar): so by actual application- up to 45% feldspar or 45% Nep Sy. (That a lot even for cone 6) Soluble salts are carried by the water content in the clay. As clay dries: the water in the center of the wall moves to the surface- which also carries the soluble salts with it. This migration appear as light/whitish areas on the clay surface. In every example you have shown thus far: the whitish areas are towards the bottom, most around the foot ring. The foot ring/bottom portion of a thrown piece is typically the last to dry: making it more susceptible to soluble salt migration. There can be other causes as mentioned; but contaminated slip in my opinion would appear randomly at any portion of the vessel- not just the bottom. Assuming all the vessels in the firing had the same stain and or oxide: that would rule out fuming. Fuming usually results when iron, cobalt, and manganese are fired together: the off gassing fumes from cobalt for example discoloring an iron bearing stain next to it. Below is a picture of serious soluble salt migration from natural clay harvested by a forum member (Hi Mary) although extreme, it does give visual context of what occurs when soluble salts migrate to the clay surface.
  11. Sorry AH, not been following the past week or so. Fuming as suggested is one possibility, but more likely soluble salt migration. Nep SY has become the body flux of choice because it is cheap; but also has up to 14% soluble salt (sodium). Over- firing would effect the piece on a broader scale I would think; with blistering and bloating being the more common defects. As you recall the testing on Little Loafers a year or so ago; soluble salt migration was severe enough to cause glaze defects. Migration in a clay body; tends to collect in the areas that take the longest to dry. From the effected areas, it appears to be following that pattern. One question: did this occur in previous batches of clay? Is this a new clay batch, or a change in clay suppliers? T
  12. Joe: i have firedmost rare earth oxides: prasdyium, holium, yttrium, neodymium, and a few others- along with silver nitrate. (Love how spell check changes when I try to type them) You said the key phrase "oxidation state." FeO4 to FeO, etc. You will find the oxidation state most relative to ceramics and glazes. "Redox " is your starting point, and from there oxidants and reductants. UC Berkeley came out with a Reduction Potential Chart years back for the various metalloids commonly used in ceramics. You can find that chart and discussion in this thread- Jim Fox at RiverPottery does silver nitrate reduction firing: his earlier background doing reduction firings before his obsession with crystalline glaze. As mentioned; bismuth is often used but I find vanadium pentoxide far better for oxidation ( not food safe) Vandium has an O5 lattice, but I have been looking at silica polymorphs with O chains up to O(52). Relative to crystalline glazes, not sure of any other applications. I know of a few who have tried gold and yellow cake (not food safe). I have little doubt that somewhere in the world; some Potter has fired every element they could find. Tom
  13. Great color combinations. Population is proportional. Growth rings with featuring- good work.
  14. Predicting color break in relation to anticipated glaze run is a science of its own.
  15. Population is right- niece piece.
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