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RuthB

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About RuthB

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    Advanced Member

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  • Location
    Charleston, SC
  • Interests
    Clay, Glazes, Kilns, Firing, Marketing, Teaching

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  1. My 8 year old Shimpo was getting slower and slower. I called Shimpo after trying to adjust the potentiometer. That’s when I learned that it needed a new control board for $317.00. I mostly handbuild so the wheel was not used daily. I did not know that the capacitors on the control board are like a battery and the wheel needs to run to keep them charged. Sitting idle decreases their life span. Am I the only one not aware of this? Is this so with all the newer wheels? My 40 year old year old Brent has been repaired once. I bought the Shimpo for the quiet Thanks to all. Ruth
  2. Great idea! I have made bats from the interfacing used in sewing, available from a fabric store. It's available in various thickness and stiffnesses. I then brush porcelain slip on both sides. Great bats, easy to peel off, take no room to store.
  3. I'm thinking the same thing. The clay does stick to the bat and there may be some drag possibly increased by the wooden tools and the dry clay causing tension in the base. It sounds like it doesn't always happen, but often enough to be a drag ( no pun intended). As Rae suggests doing a little trimming on the back would remove this clay before it becomes a problem in drying. You may want to add 1/8" in thickness to your platters so that you have enough clay to trim off. Alternatively, don't throw them at all. Cut a piece the desired size from a slab and flip on to the bat. Attach to the wheel head and add a coil to the edge and throw just the rim. Wire off and dry on slats.
  4. Have you made any videos of the roller tools in use?
  5. Your point is well taken, re squirting clay. To clarify, when opening, I'm pressing from both the top and side of the opening, so the clay can't squirt anywhere.
  6. Compression and alignment go hand in hand. Compressing the base aligns the particles through the base. Hamer and Hamer (The Potter's Dictionary of Materials and Technique) have some interesting points to make about the difference in drying shrinkage vertically through the thickness of the base as opposed to horizontal shrinkage across the base because the particles are aligned differently in walls vs. the base. Somehow, there is uneven shrinkage from the rim to the center happening during drying in these plates. As you wrote, it's always helpful to see how a piece is thrown when figuring out a solution. I think it would be helpful to see a video of the throwing of these pieces. Is there a lip to these plates? How is it made?
  7. The root of cracks such as these is found in the opening process. The clay and the metal wheel head have a terrific attraction for each other. If you opened the clay by starting at the center and pulling out to the edge, clay directly in contact with the wheel head the clay does not move uniformly from the center. The clay particles in the base will not be lined up as they are in the wall at the completion of throwing. The shrinkage will be uneven from the sides/edges to the center resulting in the cracks such as yours. To insure that the clay particles are lined up in the base as they are in the walls, extra attention needs to be given to the base by moving your hands from the edge back towards the center so that the base is subjected to similar pressure to the walls. I also am careful not to open by pulling the mound out from the center. I gradually enlarge the opening by pressing straight down on the edge so that the clay moves outward little by little. The base is also compressed with each move. I finish by going back and forth on the base several times, moving toward the center more than outward. Alternatively, you can leave a goodly amount of clay under the base to be wired off, removing the unaligned clay before making the foot. I prefer the first method. Hamer and Hamer has a great discussion of cracking in their Potter's Dictionary. Let me know if my explanation needs more explaining. Ruth PS. Any reasonable even drying will not cause these cracks.
  8. Babs

    Nice to read your words again RuthB

  9. Plates, platters, tiles can be stacked on edge leaning against the kiln wall, avoiding the element. Or a kiln post can be leaned first as a buffer. In this way, quite a few can be leaned, including leaning stacks against stacks Cracking problems are reduced as well. Check YouTube for some good videos on stacking flat pieces in this way all around the kiln wall, staggering stack against stack. Use the top shelf if post height is a issue. I stack anything that reasonably sits in or on top of another, bowls, mugs, etc. Three pieces max, unless it’s rim to rim or foot to foot. This guideline must have made its way into my DNA by now.
  10. I’ll make it this weekend and let you know when it’s up
  11. Plates can be subjected to a lot of stress during making that doesn’t show up until the firings. Plates that have been made by mostly flattening the clay with an outward motion are most susceptible to cracking, especially if they do not have a foot. There is a tremendous attraction between the clay and the metal wheel head and clay that has been stretched out against the wheel head will be subjected to competing forces. You’re moving the top part of the clay outward while the bottom is doing its best to stick to the wheel. Leaving enough clay to cut a foot on the bottom gets rid of the stressed clay. It also helps to move the hands back inward toward the center at least as much as you move them outward. Uneven drying can also cause cracking. Dry slowly, so that the rim does not dry before the center of the plate. A donut of plastic wrap around the rim will help. And make sure the plate is of even thickness. Thick and thin areas will dry unevenly. Slabs should be turned and flipped during the making to prevent similar cracking issues. Ruth Ballou
  12. Another option is to use a bulb syringe and a 1- 2” brush on the wheel. This technique allows large pieces to be glazed with a cup or so of glaze. The syringe is used to supply a continuous flow of glaze to the brush. Hold the filled syringe just behind the brush and gently and steadily squeeze it to supply the glaze to the brush as the wheel turns at slow to moderate speed. Too slow and the brush will not be able to evenly disperse the glaze. Too fast and you’ll encounter a dry brush with insufficient glaze to disperse. Do the back of the plate first, then flip and do the inside so that the rim will not be disturbed. I usually cost the rim first and then go inward. Refill the syringe as needed. Three passes is usually enough, but that depends on the thickness of the glaze.You can also add CMC to a couple of cups of glaze to make it brush-able.. CMC needs to be mixed with hot water in a blender before adding it to the glaze. Replace about 1/3 of the water with the CMC mixture. There are also a couple of commercially made brushing mediums, Spectrum Brushing Medium or APT II... though I have not used either of these. I can make a quick video of the syringe/brush technique if you’d like try it.
  13. Thanks, Mark! This looks like a great system. In the past, I’ve used a cheap shop vac placed outside with a long pool hose duct taped to the unit. Not surprisingly, it doesn’t last long and is a pain to set up. Thanks for introducing me to cyclonic separators. Is the cyclonic separator the $99 DIY Oneida kit or the $1000 one? Thanks, again Ruth
  14. I am considering a couple of options for dust removal and cleaning. Is anyone familiar with the Dustless wet/dry HEPA vacuum? http://www.dustlesstools.com/dustlessvacuums/HEPAVacuums/hepa-vacuums.php. It’s advertised as being great for drywall dust. It looks to have some nice features. It will vacuum wet and dry without changing the setup and has a longer than usual very flexible hose. However, I cannot find any independent reviews. The second option would be a central vacuum type system with the unit installed outside the studio. I have a small one in the house, but would need a heftier unit for the studio. Any recomendations as to brand? Thanks, Ruth
  15. Hi Chris, I took a course with Curt Benzle this fall and learned a ton about working with thin colored clay. He leads a fantastic workshop. Problems with things falling apart are usually that the clay is either too wet or too dry when joining. Since you're having problems with delaminating, my guess is that it is too dry when applied, or not evenly wet and you've got wet and dry areas. How are you wetting the clay. Which side. How are you sealing them together. One idea that might help would be to place all the layers between two pieces of cotton sheeting and gently roll and flip them, and roll again. And you you might start a bit thicker than you want the finished product to be and roll it down to the final thickness. I'd love to know if this helps. Ruth
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