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Everything posted by glazenerd

  1. Finally put twelve pounds on the wheel, my first time over 5-6 lbs. my final conclusion was: I would rather make clay than throw it. Turned out - so so. 

  2. I will be studying/testing stoneware clay body limits shortly: next month or so. Input from stoneware users would be most appreciated. I not only need formula limits, links to recipes, or you can PM them: but also properties you find beneficial or undesirable. From the research I have done so far on c10 bodies; the general range I am seeing ( in molar) Alkali 2.5 to 2.75% Total Flux 3.6 to 4.0 Alumina 19-20 SiO2 70-75 (would assume c6 is 10% higher in flux) I did not list iron (Fe) or magnesium (MgO) ; which can vary widely pending on the clay used in formulation. Stoneware can be groged or not: what % do you find most beneficial? Light. med. or heavy. Do you think mullite grog works better than sand? How important is color? iron red, deep orange, tan to brown range...etc? Is light speckling more attractive than heavy speckling? Nerd
  3. Stoneware Limit Study

    Unfortunately, I have not been able to edit my picture size-yet. Edit button does not come up when I double tap pic. This piece is just slightly larger than a shot glass: 1/8lb. of clay perhaps. Spent perhaps 30 seconds forming it and then into the hot sun it went. All I know at this point is: WOPL = 29. Nearly zero plasticity. All material passed through 100 mesh screen, and less than half through a 200 mesh. From that: alumina 30%, silica 45%, iron 12%, potash 5-6%, titanium 3%. All guesses of course, but comparing the WOPL, color, and mesh sizes to my extensive clay database: close. Will do more formal testing once I figure out if it produces the color and effects I want. Threw away a couple thousand test bars few months back, so pardon my refusal to make more at this point. Nerd Edit: I am wondering if this is a chlorite group/ clay. 2:1:1 with double tetrahydra inner layers: iron fe2 / fe3. This is close enough to the Arkansas border, where chamosite deposits are common. If that holds true, then iron levels can be over 20%.
  4. Mixed up a porcelain and stoneware body with the high iron clay from the old brick yard. Already fired 100 gram samples, now for the 1000 gram samples. For some odd reason I sprinkled some 50 mesh grog in: get out of my head John. 

    1. Joseph F

      Joseph F

      Nice. I am about to fire some clay myself. Fun Times!

    2. LeeU


      Very funny (grog/John).  Tempting to run out and buy some Grogzilla and mix it into Southern Ice. 

  5. Stoneware Limit Study

    Cone 6 firing to 2232F, no hold produced this: 50% raw clay, 25% silica! and 25% potash spar. One area has a coat of temmuko, then a raw area that self glazed, then a coat of white on the back that looks nasty. So there has to be a fair amount of spar in the clay: it self-glazed in the raw areas. Now I tend to think there is more than 12% iron! with a fair amount of titanium. At this point I am content enough to have a raw sample analyzed. nerd
  6. Na5AlO4. sodium aluminate Nep Sy precipitates 14-20% soluble sodium salts. Notice the complaints about black specks have increased over the last five years as Nep Sy has become the flux of choice. Normally soluble salts would form white crystalline nodules or powders in clay or glazes as they dry. However, every time sodium (Nep Sy) comes in contact with moisture, hydrolysis occurs: IE- hydroxols. So sodium hydroxide is coming in direct contact with aluminum ( wheel head) so instead of precipitating as white powder, it is picking up alumina to form sodiumaluminate that produces black/silver specks. my best shot..Nerd
  7. Brandee: TY for reporting back, always good to hear about the final remedies.
  8. Stoneware Limit Study

    I have been making trips to old brick mines across Missouri on and off all spring. This past week, I visited one that had been closed for over a decade. They made dark brown and nearly black bodied bricks: the reason it got my attention. I collected nearly 600 lbs. directly from the adjacent clay pit. Going to fire this 100 gram test cylinder tomorrow. I suspect the iron level is above 10%, because I can see signs of oxidation on the sample already. One level cup weighed over 400 grams, as a comparison OM4 weighs 253 grams per cup. This is a ball clay by the way, it is not fire clay. nerd
  9. Neil: the body is rather obvious in application. 10% would be tooth, 30% would be dentures. Clore: you are approaching it in the right way: comparing chemistry to the closest chemistry. Perhaps ask your local supplier if they have a product anywhere related to a finer mesh grog. Molochite is sold 120-200-325 mesh. The recipe does not state which mesh, although in the States 200 is the most widely available. Nerd
  10. I am struggling trying to understand why molochite is even in this low fire recipe. Molochite is a calcined, high temp grolleg. (Cone10-12) Nerd
  11. Indie and go fund me efforts

    As with any public venue created with good intent, it is quickly over-run by those with wrong motives. There is no screening process, so it's donor beware. To Mea's point: there are disciplines and lessons that can only be learned by going through the fire. Being a fiercely independent soul: I make and pay for my own way, and with that comes the expectation of having no expectations or desire for others to help. Then when others do offer to help, it then becomes a blessing of kindness: even though I decline. Nerd
  12. Glaze aftertaste

    Julie: then borrow some porcelain from a potter friend and make a few small cups . Glaze using those mentioned: if there is no after taste- you are down to a clay issue. strange question perhaps, but it has a purpose. Does the water you use to throw develop a pungent smell in a short period? The darker the clay body: the higher the sulfate/ carbon content. Organics in a clay body develop a musty/rancid smell in the throwing water in a short period. If you change water everyday then you probably have not noticed it. If you let it sit a few days, you will. Nerd
  13. Joseph: that is one of the traditional remedies: but not what I had in mind.
  14. Glaze aftertaste

    John: I would like to add a caveat to this topic and to the "weep" test. Stoneware clay bodies hold moisture on their inner platelettes, whereas porcelain only hold moisture on it.s surface. An example: OM4 ball clay will hold 35 grams of water in every 100 grams of clay material: without showing any signs of weeping. That number is much lower after a firing: if immature it would be in the 3-5 grams of water per very 100 grams of material. Simple math: an 1lb. Mug could conceivably hold as much as 12-20 grams of water without showing any signs of weeping. Compound this by the exterior glaze being vitrified, and trapped water unable to pass through it. So while the weep test is one method of testing, it is not a definitive test for a piece holding/releasing moisture in the clay. If a scale is accurate enough: fill the piece with water and let it sit 24 hours and empty the water and towel dry. If the weight before and the weight after differs: it is holding water internally. Immature stoneware would be highly susceptible to this problem. i would recommend making a 4x4 tile using this (or any) clay and fire it to maturity unglazed. Let it sit in water 24 hours and towel dry before weighing. If the weight differs before and after the soak period: then you know with certainly the clay is holding water. This differs from the standard boiling test: but it will give a quick insight into the problem. Hate to be offensive, but I suspect the after taste is from fungus growing inside the clay walls. Nerd
  15. Joseph: as soon as I finish working on a drying spritz: will deal with the GB issue. My last test with the spritz: the test piece dried within 90% even-ness from top to bottom. Going to test a few bowl, platters, and other shapes before I realize that info. I do not think the GB properties will be too tough to solve. Nerd **edit** testing to date has been without using plastic covering.
  16. V-gum is a binder for glazes: that like any gum keeps them in suspension. In this case however, because V-gum also has a tacky quality, they are using it to help bind glaze to the piece, and as a brushing medium. I started to once fire some time back in order to save time, save element life, and to save money. I developed my own nerd suspender that does what V-gum does for 1/2 the price. My schedule is: 160f to 1150F ( gets you past quartz inversion at 1063F) 250F to 2050 F 125F to 2230F ( no hold in smaller kilns) i do not have pin-hole issues, good uniform melt, and vitrified. Not a fan of 2190F with long hold, although it is common practice in pottery.
  17. An old thread from Clay Art on the topic:
  18. John: I wonder how many modern potters have the patience to spend 1000 hours carving the details in a single vase? Today we program a machine that will carve with precision in minutes. (Adelaide Robineau- scarab vase)
  19. Correct Tyler- my beloved I-pad wants to auto correct everything. several liability. I was drug into a lawsuit years ago between two land owners arguing over property boundaries. A corner of my ground touched theirs, so one attorney enjoined me in the suit. They were suing over a tract that was 1 foot by 120 foot.
  20. Sputty: Doat fired his first pieces in crystalline in the late 1880's: which predates the filament link you posted. I have been to the university museum: the old university pottery where he worked from 1905 to 1915. Having read many of his notes and firing logs: I have yet to find any references to any type of measuring devices. I appreciate the attempt, it did answer other questions I had. Still trying to figure out how he knew it required zinc and silicate in exact percentages.
  21. And people wonder why I only make crystalline tile. The legal term is "severability", a nice little caveat that Senators wrote into the law to repay their large corporate attorney donors. Which basically says if you touched a product in any shape or form from the time raw material was taken out of the ground until it lands on someone's table: you can be enjoined in a suit.
  22. Easy one for me: Taxtile Doat of crystalline glaze fame. (1890-1917) 3 questions. 1. How did you figure out the zinc/silicate ratio required? You had no glaze calculator, you had no x-ray diffraction, atomic force microscopes: how did you know? 2. How did you figure out that you needed hold ramps at certain temperatures to make crystals grow? You had no kiln sitters, no programmers, and no pyrometers: how did you know when you hit the hold temps? 3. What made you decide to fire crystalline pieces in saggars? Was it intuition, some oddity you noticed in a firing, or previous experience with another glaze? After I finish with Mr. Doat, I have a few questions for Maria Longworth Storer. Truly pioneers in pottery: they had no reference books, no glaze calculators, and no internet to look up any aspect of any given ingredient. They had little information on chemical analysis, molecular weights, melting temps, or COE data. How did they figure it out? nerd
  23. What is this?

    Min: my supplier has a section for firing beads in his store. I saw something similar to these laying there. I do not do beads, nor have I seen these before. Just a random thought.??????
  24. Elaine's Cone 6 Porcelain from Sheffield

    Sunset: As a point of curiosity for me ( I track clay issues): I would like to know if they used sodium or potassium as a flux. Giving the drying and cracking issues; I would tend towards sodium. The trend has been towards Nep Sy for the last two years because potassium is 3-4 times the cost now. nerd
  25. New Forum

    Mea: I was trying to edit the picture I had posted. I double clicked the image, but did not see any pop up window by which to edit. Both my desk top and lap top are windows based. They are older versions (7.0 I think), left overs when I closed my office. The wife's I-pad is an Apple, so I would assume Mac. Of course what I know about computers, consists of knowing where the on/off button is.