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Rachel Hawkins

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  1. I usually use a buff stoneware - any excuse to wedge less, I'll take! I think I'm definitely trapping an air bubble in the middle because I've been putting the clay down on the wheel in a totally flat cone shape. Will try with a rounded edge and really hoping that helps! Plus working on trimming to ensure even thickness across base, walls and corners! Thanks so much for your help!
  2. Thank you!! I've looked at cross sections of my pots before and you're completely right, even if the base and walls are the same thickness the way I trim seems to leave a solid hunk on the outside corners. Hadn't ever considered trimming that part from the inside, will try it now!
  3. Thank you Pres! I think this might be a big part of my problem. I've been throwing the clay onto the bat in a flat-bottom cone shape and I think making it convex will *hopefully* really help!
  4. Thank you Mark! I will try to compress more during the forming stages and am excited to try the spoon trick too. Do you compress from the inside bottom of the pot or on the outside bottom? I'm using Laguna Buff 45 stoneware, I recently tried white stoneware and got no cracks in a batch of 10 pieces (unheard of for me with the buff) but am not yet sure if that was a fluke or if perhaps the Buff is part of my problem.
  5. I've been using Laguna Buff 45 for the past several years but recently switched to a white stoneware - I think 65 - and got no s cracks on those pieces. So now I'm using more white clay and seeing if that makes a difference. And r.e. shaping - I'm wondering if the cup shape I go for - basically a wide cylinder with 90 degree wall to base, very straight / sharp cornered piece - tends to lead to more stress and cracking? Maybe more rounded shapes hold up better during the drying process?
  6. Hmm, I think you may be onto something r.e. my base being thicker than the walls - I think they usually are. It's quite possible that the 25% of my pots that aren't cracking are the ones that are the lightest / with the least heavy base. I'll try trimming a bit more from the bottom and see if that makes a difference. I've been using Laguna 45 Buff for the bulk of the s crack years... I recently used white clay for the first time (I think maybe 65 White Stoneware) and got no s cracks on those 10 or so pieces, which is interesting because it seems like most people have had more issues with s cracks with the white clays.
  7. Thank you, all so helpful! I will try putting additional pressure on the outside the clay per your suggestion r.e. the sharp corners! I also hadn't tried making the ball of clay convex - the bottom is always completely flat when I put them on the bat, so maybe adding that curve will help eliminate the air bubble / vacuum problem.
  8. Hi! I have been making pots for about 7 years and in the past 4 have struggled with small s-cracks appearing on the bottom of about 75% of my pots. The s-cracks are usually around a half inch long, thin, and only on the underside of the pot - never go all the way through and therefore the pots are all fully functional, just annoyingly cracked. In the photo attached, you'll see 3 cracked pots, and 2 planters that did not crack. My theory is that something is amiss in the center of my pots that causes stress & cracking during drying - because typically, when I make planters that have the centers removed, cracks do not appear. The cracks don't show up to my knowledge til after the bisque fire (though because my studio fires my pottery, there are usually a few days that I'm not seeing the piece before it's loaded in the kiln.) I have tried just about every remedy I can get my hands on and still can't manage to kick these cracks to the curb. My current regimen is: 1. Wedge each piece of clay (ram's head) 40x each. 2. Align clay on wheel so the spiral-y part is horizontal per this video: https://www.youtube.com/watch?v=f7oIZiXmXFU 3. Tap clay to center and use a finger to create a seal between clay and bat. 4. Add water, press down on the clay and get into flat hockey puck-ish shape. 5. Cone up and down three times. I make sure my cone is very cylindrical, with the bottom being almost as narrow as the top, which I read was important for preventing cracking. I make the top of the cone teeny-tiny and focus on getting air bubbles out of that portion. 6. During coning down process, I bring the piece back into a hockey puck shape and run my finger across the top towards the center, occasionally finding air bubbles there. 7. Bring out the walls and compress bottom religiously with my thumb, a kidney rib and my sponge. About 10 times, compressing from the outside of the base to the center. Occasionally, I'll feel little air bubbles during this step and will continue compressing until I've popped them. 8. Continue to compress and flatten bottom as I shape the piece. I don't let water sit in the piece. 9. Let the piece dry slowly and evenly on absorbent surface like canvas or foam (covered after a few hours). Dry with bottoms up once sturdy enough to stand. Something I've noticed: Often when I use the wire to take pieces off the bat, there is a small air pocket right in the center of the clay that appears both on the remaining clay on the bat (picture attached), and on the piece itself. The indentation in the bottom center of the piece is never more than 1/16-1/8 of an inch deep I'd say. It's something I trim off later in the process, but seems to correlate with the pots that end up cracking. A hypothesis: Could I be creating these air pockets during the coning up process? I.e. as I press the clay in & up the bottom air pocket forms? Maybe making my cone so cylindrical is part of the problem? Another potential hypothesis: My wedging is bad and introduces too many air bubbles. Would I be better off using clay straight from the bag? (Or, sigh, trying to get better at wedging?) Last note: I prefer a flat bottom to a footed bottom. It's possible I get less cracks when I trim feet, but I haven't really investigated. Any advice you have on ending this years-long struggle would be so, so appreciated! S-Crack Photo Bat with Air Bubble
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