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Everything posted by CactusPots

  1. It's easy to have respect for Thunnus thynnus, when he's kicked your ass and made you cry like a little girl. Personal experience.
  2. An alternative to clay cookies is to cut soft brick into cookies. You really need a bandsaw to do this properly, so that will probably kill this suggestion for a lot of people. Pretty quick way to set up a box full of exact same size thickness goodness that can be used over and over. At least until a glaze drip claims it's life. Even then the soft brick is easier to grind than clay.
  3. I've found that a miscalculation with runny glazes can cause the glaze run to soak through the kiln wash. Especially if it isn't thick enough to absorb the glaze before it gets to the shelf. I've been using grog in the kiln wash to beef it up. Seems to work. Personally, I only have one set of mullite shelves in my kiln, on the very bottom. If you aren't stuck on runny glazes or have all your glazes dialed in, this probably won't be an issue. If the glaze does reach the mullite shelf, it will be absorbed into the shelf. Then the only recourse is to grind it flush and get a thick layer of kiln wash over. Or throw it away and start over.
  4. Of course, big is a relative term. For me, 25 lbs of wet clay is big and I doubt I'll go much bigger. Most of my demand is for 8 lbs and less. I joined the 2 sections at around 1 inch thick and then pulled up to my 1/2 inch final. So maybe that's where the laminations came from. I did the joining right after the initial throw for the bottom piece. Both sections as soft as can be. No slip. ls that the ticket, or are you allowing some stiffening to get a thinner joint? So in that case the joining is pretty close to the final form.
  5. I appreciate all this feedback. I had a few beginner courses 20+ years ago, but I'm largely self taught. I mostly avoid areas that cause a lot of trouble. Like this. The delamination is entirely in the added ring section, so I'm thinking the primary issue must be in the way I opened the clay. I must have pushed a layer onto the wall when pulling it up. Not sure how I did that, but next time I try this technique, I'll have to be more mindful of that. The clay body is Laguna Soldate 60 WC843 fired to 06 1823F The color differential inside the bisque is a subject I never gave any thought to. Sometimes a pot fired inside another will have this color change on the outside. The kiln is a Skutt 1027 fired to 400 with the lid propped slightly, then closed. Fired to completion with the top plug out. Here's another example of this color. I get it pretty regularly, but it doesn't seem to make a difference.
  6. If the bricks forming the floor are loose, a better way would be to band them together in some way.
  7. My understanding of the source of the evidence of barium's toxicity was a kibbutz in Israel that substituted barium for baking soda. There has to be an acceptable level of toleration, otherwise we fall into the "no measurable level" camp. Science is really good as measuring things like lead in drinking water and there is in fact measurable lead in your water. I doubt a spoon full of red iron oxide would be any good for you. I don't get the idea of not having barium in your store of glaze ingredients. As for exposing users to it, that's what liner glazes are for, right? As for it being a risk to the potter, it's your choice, but it doesn't seem to me like much of a risk as choices in life go. I question the idea that most potters don't use barium at all.
  8. Here's another look at the pot's flaw. I just pulled on the crack and exposed this. I'm going with the "don't fire big pots on their rims". I have one left from this series, I'll try it right side up, on a waster slab, in the middle of the kiln.
  9. Throwing big pots is in fact a new thing. The pots look good to me in the green stage, I don't see any reason not to bisque fire them. We could probably have an interesting discussion on what is the proper thickness for "any" pot. I'd maintain a planter should be thicker than a bowl. The first one I fired was on its base and split in half when I threw it on the shard pile. The wall thickness is about 1/2". A better thrower (which I will be if I stick at this) would no doubt make a thinner pot, but I think it should work.
  10. At least for a while. The bottom was my big concern.
  11. Giffen Grip with a carpet pad under Maybe in a chuck with a carpet pad liner Use a bubble level to get a quick even level
  12. To get past the limitation of centering and opening a single piece of clay, what's your preferred method, assuming you do this. Throwing 2 or more sections and joining before final pulling and shaping Adding coils to a thrown base and final pulling and shaping. Is there a better way? Or do you just stop at your limitation?
  13. I don't know how it could be sticking on a layer of grog, but ok. Didn't I read here that there isn't much shrinkage in bisque? So the waster slab would be bisqued along with the pot and then high fired with it also? If I get a successful bisque, then I'd expect you could treat it normally for the high fire. I'm mainly thinking about stacking other pots inside. If I have to high fire this pot by itself, I won't make any more this size. Too much kiln space = too much cost.
  14. The pot wasn't really thrown in one piece. What makes this one different is that before attaching to the bottom half of the finished pot, the top half was centered and then pushed out entirely to the width of the bat. Then it was opened all the way to the edge with no bottom. It seems to me that I could have created a fault or fold in the clay moving the clay from the center to the edge. Rim cracks are one thing, but the spiral nature of this crack is unusual to me. Does anyone else use this method for throwing larger pots? I find 25# of clay too much to center and open.
  15. New clay. Soldate 60. Softened using a puncture method. What do you think about the spiral nature of the cracks? They tail away from the counter clockwise motion.
  16. Let me be more specific. (1) 40 degrees per hour to 120 hold 1 hour (2) 80 per hour to 200 hold 1 hour (3) 250 per hour to 1000 (4) 300 per hour to 1823 degrees. I think I will make some changes on this schedule. I'll make (3) 200 per hour to 1100 (quartz inversion is 1063) Do you really think this is a quartz inversion crack? It's not a regular rim crack, it spirals down. Something about the throwing, I think.
  17. The pot is about 9" tall and 15" wide. It's a pretty heavy pot for the size. I was hoping the thicker walls would help with warping and cracking. Planters should be heavier than bowls, etc. The 2 pieces when they were being thrown together were a good inch thick and pulled the last with stiff ribs inside and out. Then expanded out to shape. They got a couple days under plastic, then a couple more under towels before direct air drying. The other thing is that I softened up the clay using a trick from this forum of pushing holes all the way into the block of clay and adding water that way. Then wedging the bubbles out. Even if there was a streak of softer clay, I can't see it doing this
  18. This is Soldate 60 from Laguna. Pretty much my go to clay. Firing schedule is 5 hours to 400 (lid cracked) and then 5 hours to cone 06. Works good for thick hand built as long as it's dry. Shelf had a good layer of grog, so should have slid ok. I'm zero for 2 on bisque firing these. I have one more to try. I hate to waste space on either bisque or glaze firing by not having anything inside. Maybe try loading the pot in the middle of the kiln rather than the bottom?
  19. This pot was thrown in 2 pieces, first a bottomless ring then placed on a matching cylinder. Total weight was a full 25 lb bag. The first bisque on another similar pot cracked the bottom. There were other pots stacked inside, so I fired this on on the rim with other pots inside, but not touching. Fired on the very bottom of my electric kiln. I don't know what to think about this cracking. Either a fault in throwing or somehow a kiln issue. Doesn't seem like a typical rim crack to me.
  20. Available as in for sale? I'd have to dig it out. I'll post a few more on Monday.
  21. Kind of a long way to go, but if you get to price shopping, you might consider Freeform Clay in National City. My main man. No sweat to give them a call.
  22. Of course you can always free hand build feet. You just need an awesome texture collection.
  23. Point being making molds, slip, hump, slump, press, each present their own set of problems. Before we get to the actual clay part of the problems. Especially the size that these videos show. It looks like a simpler way to make a big pot, but if you look at the details, it is not. Right, you can't buy molds like that. The molds these bonsai pot makers are using are works of art of themselves. Using them is a very special skill set.
  24. Turns out my nursery accounts for my planters are looking up. People are largely stuck at home and if they have a plant hobby, that's a good release for their time. Consequently, the plant nurseries are doing well. I don't know that I'm going to make up for the lost sales from the club sales, but I'll be happy to carry some inventory into next year. From what I hear, my favorite camping in the Sierras is jammed. Some things are going to be busier than normal this summer.
  25. The only purpose of a mold (IMO) is mass production. Unless you want to produce a catalog sale item, the challenge of handbuilding is a viable option. Lots of skill sets to learn along that way as well. At least you don't have to store plaster molds that way. I've watched those videos also, and there are a lot of parts of the process that they don't show, especially the large pieces. I make planters just about every way they can be made (ceramic) and I'm challenged to the point of failure frequently, especially large pieces. Start small and have lots of plants to enjoy in your own pots.
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