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glazenerd

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  1. Like
    glazenerd got a reaction from Hulk in Short clay   
    Fix It mix for stoneware is: 80% OM4, 10% silica, 10% feldspar. 
    Add 1/2 to 1 cup per gallon of reclaim. ( sounds like you need at least a cup).
  2. Like
    glazenerd got a reaction from Rae Reich in Does calcined EPK rehydrate if it gets wet?   
    Citing the work of W.G. Lawrence, A.F. Norton, and D.D. Buttons ( all Alfred engineers)
    the question was rehydration: the application is molecular moisture: meaning H2O has chemically bonded to the crystal lattice of kaolin. As DW pointed out above- nice job!  As DW noted: once calcined, it takes time (lots), temperature will accelerate, as will pressure.  In reading the works of those three listed: the only reference made to rehydration from direct water contact was "minimal" over an extended period. No definition of "minimal" or "extended" was given. Although in reading other abstracts: 5% rehydration occurred. Note however that is 5% of the 12-14% of original molecular moisture lost in calcination.
    so why is heat and pressure required to accelerate rehydration?   Below is a quick diagram I made of a kaolin particle encapsulated by a molecule of water. Kaolin is a 1:1 clay particle: one side is alumina and the other side is silica. It has no inner platelets that will absorb water like ball clay does. Ball clay is a 2:1 particle. Kaolin will only hold water on its surface, and will not absorb water unless heat and pressure is applied. The resistance to absorption is part of the "stretched membrane" theory introduced by Norton in 1948. A molecule of kaolin is fractionally larger than a molecule of water: so the water molecule is slightly stretched as it encapsulates the kaolin. Applied, this means the water molecule is under increased surface tension which effects how the clay/ water film reacts.
    the two inner circles are a kaolin particle ( alumina and silica) The outer ring to the inner jagged ring is a water molecule. The space labeled "ionic disorder" is the area between the kaolin and water. This area is where negative or neutral charges from the kaolin react with water: which is a dipole. (Long winded discussion on dipole here) This disordered ionic area creates a chemical barrier which retards moisture absorption. Again, kaolin being a 1:1 particle naturally resists absorption.
    edit addition: sorry got called away.
    temperature accelerates rehydration because temperature increase is a direct measurement of atomic motion. The "disordered area" becomes more organized  in relation to positive and negative arrangement of atoms. 
    Pressure becomes relative because increased pressure closes the disordered space between kaolin and water.
    T
  3. Like
    glazenerd got a reaction from Rae Reich in Narcissistic artists sell more art for more money   
    Larry:
    i "liked" both articles; so maybe post one on "conflicted."
  4. Like
    glazenerd reacted to docweathers in Narcissistic artists sell more art for more money   
    However, It my backfire


  5. Like
    glazenerd reacted to docweathers in Narcissistic artists sell more art for more money   
    Strut your stuff
     
    See article attached

  6. Like
    glazenerd reacted to Gabby in Article out today   
    I don't know in which section of the forum this belongs, but I saw it in LitHub, which is a newsletter I read that flags interesting new writing.
    https://lithub.com/on-the-intoxicating-alchemy-of-pottery/
  7. Like
    glazenerd got a reaction from lgusten in Makin a living with electric kilns at cone 6?   
    The difference between reduction and oxidation are the number of oxygen molecules left in the glaze. Actually I would be focused on a complete melt. Been playing with cone 3 for a couple of years now-doable. Fear not: technology will come to a kiln controller near you: "Alexa, fire me a nice red glaze."  
    T
  8. Like
    glazenerd reacted to Rae Reich in Colored terra sigillata turns hazy   
    There are several formulas of black Mason stain. Each reacts differently in conjunction with glazes, perhaps there are differences in conjunction with clays or techniques. 
  9. Like
    glazenerd got a reaction from Russ in Slipcasting for tiles?   
    Moh
    look for a porcelain with a shrink rate in the 10.5 to 12 range. High plasticity in porcelain = higher memory.
    unglazed once fire: try this stacking arrangement. Less drag, more pieces per square foot. I rarely loss a piece to inversion using this firing  stacking method.

    i make this piece both ways: slab rolling then adding the raised deco. I have also slip cast this as well.

    this piece starts as a 14 x 16, and ends up 12 x 14
  10. Like
    glazenerd got a reaction from Russ in Slipcasting for tiles?   
    Moh
    look for a porcelain with a shrink rate in the 10.5 to 12 range. High plasticity in porcelain = higher memory.
    unglazed once fire: try this stacking arrangement. Less drag, more pieces per square foot. I rarely loss a piece to inversion using this firing  stacking method.

    i make this piece both ways: slab rolling then adding the raised deco. I have also slip cast this as well.

    this piece starts as a 14 x 16, and ends up 12 x 14
  11. Like
    glazenerd got a reaction from Russ in Slipcasting for tiles?   
    Moh
    look for a porcelain with a shrink rate in the 10.5 to 12 range. High plasticity in porcelain = higher memory.
    unglazed once fire: try this stacking arrangement. Less drag, more pieces per square foot. I rarely loss a piece to inversion using this firing  stacking method.

    i make this piece both ways: slab rolling then adding the raised deco. I have also slip cast this as well.

    this piece starts as a 14 x 16, and ends up 12 x 14
  12. Like
    glazenerd got a reaction from Russ in Slipcasting for tiles?   
    Moh
    look for a porcelain with a shrink rate in the 10.5 to 12 range. High plasticity in porcelain = higher memory.
    unglazed once fire: try this stacking arrangement. Less drag, more pieces per square foot. I rarely loss a piece to inversion using this firing  stacking method.

    i make this piece both ways: slab rolling then adding the raised deco. I have also slip cast this as well.

    this piece starts as a 14 x 16, and ends up 12 x 14
  13. Like
    glazenerd got a reaction from dnarthun in Makin a living with electric kilns at cone 6?   
    Shawn:
    As with all things pottery: the reasons for gas or electric vary according to need, utility costs, and desired glaze effects. I have a 15.5 CF electric front loader: it holds a fair amount of product. My property is zoned agriculture and we have a rural co-op electric supplier. They recently raised our rates to 8 cents a kilowatt: still dirt cheap. I can fire a cone 6 glaze cycle for around $10; which is probably as economical as gas. Front loaders are pricey; so that comes down to save your back or save your bucks.
    if you go electric; then by a production kiln. These kilns have thicker brick, and additional fiber; both of which save $$$$. When you fire big kilns; you save money by not pushing them. In a glaze fire from bisq: I will ramp at 300F until I hit 2000F: then 120f until I hit 2230F. The big power draw is the upper end of the firing: which can eat 40% of the cost for the last 200 degrees.  
    The type of pieces you plan to sell will also play a role in kiln size. I drew out the interior of the kilns I was looking at: and figured out how many would fit the chamber size. Homework time.
    t
  14. Like
    glazenerd reacted to Patrick in Used fire brick changed my plans   
    More progress. Got the back wall put in. Have a few gaps to mortar up, but I'm satisfied.  Hope everyone is well.
     


  15. Like
    glazenerd got a reaction from terrim8 in Used fire brick changed my plans   
    That arch looks strangely familiar. Always wondered where they got the idea for this

  16. Like
    glazenerd got a reaction from Rae Reich in Clay thickness, in relation to physical strength   
    I see these defects all the time on thicker pieces. Slab roller just does not have the compressive strength to compact them. You can also tell by the discoloration at the center cavity that heat work was not complete.

  17. Like
    glazenerd got a reaction from Rae Reich in Clay thickness, in relation to physical strength   
    I see these defects all the time on thicker pieces. Slab roller just does not have the compressive strength to compact them. You can also tell by the discoloration at the center cavity that heat work was not complete.

  18. Like
    glazenerd reacted to Rae Reich in What temperature is OK to crack kiln open   
    Uneven cooling can happen in gas kilns as soon as a peep is left out, a door is cracked or a brick removed because it automatically creates a draft, drawing air in from the burner ports, unless blocked.
  19. Like
    glazenerd reacted to Mark C. in What temperature is OK to crack kiln open   
    Other things to consider are kiln furniture issues-My advancers shelves do not like quick cooling . I have some friends with a 30 cubic front loader gas kiln with advancers like mine. They kept having cracked corners off the back bottom of the kiln for a few years. They live in the sticks and are shelve taught . They called me after cracking many 12x24 advancers I asked about the cooling cycle. They said they always pulled the damper at 1000 degrees. I Suggested firmly to stop that-no more racked shelves. At about $250 a shelve delivered that cost them a bundle. 
    They also do not like small point stilting-meaning a high sharp point on a post or shim can also put them under tension and crack the corner off-especially when the stack is 10-15 shelves tall
    Pots depending on size and form can or cannot take the fast up down cycles. Nothing like a power train kiln to produce wares fast. 
  20. Like
    glazenerd got a reaction from Bill Kielb in Cristobalite   
    Fair amount of truth to that. Our generation are the beneficiaries of the research and corrections made by them before us. Problems from cristabolite inversion are rare; but not gone. Most commercial bodies have been formulated to deal with this issue. However, like all things pottery: still some squeakers once in awhile. I see it more when older recipes are used. Operator error as well. 
    Tom
  21. Like
    glazenerd reacted to LeeU in Choosing clay bodies for jewelry   
    Yeah-where is Pugaboo? Haven't heard from her in a while!
    I am not well-versed in making ceramic jewelry re: volume or length of time, but I have been making some for about 2 years. I prefer porcelain for brooches and pendants-cone 5, and Bella's Blend (a fairly true multi-range body/stoneware) for earrings and rings.  Do you have a sample photo you can show? You may have to resize it--450 pix H & W is good for posting.  For me, the way to find out what works and what I like to work with only comes about by testing and trying different bodies..there are many attributes to consider in terms of what is "good" for making adornments, not the least of which is personal aesthetic and fitting into or developing a market for a particular style. 
    Just for fun, here is a brooch of a cat face, "warm" porcelain (not the whitest), with gold in the incising and inset "diamond" eyes.  About 1.5 "

  22. Like
    glazenerd got a reaction from Rae Reich in Choosing clay bodies for jewelry   
    You did not list a cone fire: which makes a difference.
    as Liam suggested : large particle clay bodies will not work. This alone would knock out most (if not all) stoneware bodies. A high plasticity porcelain is smooth; but that comes with shrinkage rates at 13-14%. At low fire temps: you should find several smooth earthenware bodies. Low fire produces a softer fired body, but should be okay for jewelry. For jewelry, working properties would be as important as fired density. Low fire bodies have higher COE values than cone 6-10: so glazes need to correspond with cone rating.
    i do not buy commercial blends, so others will have to chime in on that.  Where is Pugaboo when I need her.
    Tom
     
  23. Like
    glazenerd got a reaction from Bill Kielb in Clay thickness, in relation to physical strength   
    Hitch:
    the term you need to research is MOR (modulus of rupture) as LT pointed out, particle size is a major player in green and fired strength. For instance in green strength: a 0.75 micron ball clay hovers around 400 psi. A 0.30 micron ball clay can approach nearly 800 psi. Particle size distribution is a common theory in clay formulation: but packing density increases psi.  Large particle/ mesh weakens a body because of the porosity. Glass/mullite is stronger, increasing the content allows for thinner walls. Here is a place to start
    https://books.google.com/books?id=vtzkmgkvYj8C&pg=PA10&lpg=PA10&dq=modulus+of+rupture+for+clay+bodies&source=bl&ots=SWcZDpO-rL&sig=ACfU3U2UxN8hNvngWGeLi5hFKByZ9RvZ3A&hl=en&sa=X&ved=2ahUKEwi40cTx2JbgAhUE94MKHRwYCiUQ6AEwEnoECAkQAQ#v=onepage&q=modulus of rupture for clay bodies&f=false
  24. Like
    glazenerd got a reaction from hitchmss in Rolling Pins   
    Being married: I do not allow rolling pins in the house.
     
    Nerd
  25. Like
    glazenerd got a reaction from hitchmss in Rolling Pins   
    Being married: I do not allow rolling pins in the house.
     
    Nerd
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