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About Min

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    full time potter

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  1. I can't really see drying out new clay just to slake it down, and wouldn't want the dust from pulverizing it. If you do want to add unused clay, and can't get it powdered, I would just use it straight from the box and mix it with your wet scrap in the pugger, run it through a couple times to get it blended together and try it. (try bending a coil around your finger, clay shouldn't crack) If it's still not plastic enough I would leave it for a couple weeks and see if it's improved. If it's still short I would add more fresh unused clay and try again.
  2. Thanks for posting my question Pres. Mark, do soap dishes sell better for you than your soap pumps? My kiln fillers are quite small, between 2 - 3" tall or wide. Teabag/ring dishes, mini bowls, and no trim mini tubs and mini jugs. The jugs and bowls sell the best for me. Jugs for warming up maple syrup, melted butter, cream, salad dressing etc.
  3. I don't think so. Dry clay slakes down far quicker than trying to re-wet semi moist clay but those fine particles still need to get wetted down which takes time. By not letting your clay dry out the fines are already wetted.
  4. +1 for this. The throwing water plus the slip/slop in the splashpan contains the fines. Since the smaller the clay particles the more plastic the clay is by adding the fines back to the clay it will help with restoring the plasticity to the clay. If you don't have enough throwing slip/splashpan slop to fix a short body you can add some ball clay, won't take much. (or blunged bentonite or macaloid if you are using porcelain) If your pugger has a vacuum that helps get the water in=between the clay particles to wet the small (plastic) particles, if not then pugging the clay on the wet side and letting it sit for a couple weeks will help also.
  5. HTP is a Tennessee ball clay, looks like Iceberg has higher alumina and silica than EPK, particle size is about the same.
  6. Min

    Advice for 1st glaze firing?

    Yes. If this happens then note the temperature when you shut it down. If the cone isn't down all the way at the beginning of the soak I would let the kiln continue with the soak. If the cone tip gets to about the 3:00 o'clock position (or 9, depending on which way it's facing) adding a 10 - 15 minute soak probably will take it to tip touching shelf.
  7. Min

    Kiln Wash Mistake

    The Campana recipe works fine without any Darvan. Just use enough water to make a pouring cream consistency.
  8. Min

    Advice for 1st glaze firing?

    Which controller do you have? With the Genesis you can add 5 minutes while in a hold or increase temp while in a hold.(page 17 of this) If it's an older controller then you have to quickly shut if off then restart it. As long as the temp has dropped below the "set point" for the soak it will restart and go to the last segment. There might be another way but that's how I do it. Can you talk with someone at your studio and confirm what they are firing to? Wasn't sure if you meant closer to cone 5 or 6? If it's cone 6 then I would use the med speed glaze fire to ^6, watch the cones near the end of the firing and shut it down when 6 is down if that happens before the soak. (Can do a tc offset for your next firing to allow for a soak if it's firing too hot) If 6 is nearly down adding 10 minutes would be perfect to get to ^6.
  9. Min

    Advice for 1st glaze firing?

    Thermocouples can vary, I would put a cone pack in front of the spyhole and monitor it near the top of the firing. (wearing eye protection) Increase the hold time if necessary to bring the ^6 down. (In my kilns 10 minutes is not enough to go from cone 5 to cone 6) There is a lot more mass in the 1027 which in itself will slow the cooling down more than your 818, might be fine but might need to add a bit of a slow cool depending on how the glazes look.
  10. Moisture in the pots will cause them to blow up. Put a room temperature pot against your cheek and if it feels cool on the bottom then it's still not dry. If you used a cone 6 glaze firing program it likely went too fast through the lower temperatures. There are charts here showing what the ramps are using the controllers that are on the L&L kilns. If you do a mash up of a ^04 bisque with an average ^6 glaze program you would have something like this: (all in F) 80 / 250 / hold for 2-3 hours if you are not sure the pots are dry or if they are thicker than 3/8" or so 200 / 1000 / 0 hold 100 / 1100 / 0 hold 180 / 1676 / 0 hold (from here on it goes to the latter part of a med/fast ^6 glaze firing schedule) 400 / 2000 / 0 hold 108 / 2130 or until cone 6 is down kiln off
  11. It's fine to start the kiln while still warm. Going forward, if you are not glazing you can single fire (bisque and glaze in one firing) and go to whatever cone you are "glaze" firing to. This type of single firing goes slow like a bisque up to your bisque cone/temperature then proceeds with the remaining firing going at the schedule for the glaze firing from the peak temperature of your bisque to your final "glaze" cone/temperature. Do you have a programmable controller or a manual kiln and what cone are you firing to?
  12. Min

    help needed re slip casting

    Hi Julia, Okay, so it's not too much deflocculant but not any at all that is the problem. There is just too much water in your slip. Casting slips contain far less water than a slip made with just clay and water and yet look just as fluid. There is an article about using your claybody and turning it into a casting slip here, and a short explanation of mixing casting slips here. For red earthenware I would suggest using Darvan 811. It's easy to add too much deflocc so you need to be able to accurately measure the deflocc and slip as you find the right amount to use. (Some pugged claybodies don't work well as casting slips as there can be too much bentonite in them which causes them to cast too slowly.)
  13. Min

    help needed re slip casting

    @eoteceramics, can you post your recipe? I think you have probably added too much deflocculant. You can just wipe those fuzzy salts off the plaster with a sponge, don't need bleach.
  14. In claybodies the positively charged barium ions combine with the negatively charged sulphate ions and stop the sulphates from precipitating to the surface of the pot as the combination of the two produces barium sulphate which is insoluble. For a clay body with soluble salts and no barium the longer it takes for drying the more soluble salts will migrate to the surface. I think that the darker the clay the easier it is to see the soluble salts but they are probably in a lot of clays. As Hansen says barium "may" be needed. I've never had an issue with ball clay in glazes and soluble salts forming on the surface of glazes.
  15. @vivk, are you looking for an underglaze or a glaze? Your title says underglaze but then I read this so wasn't sure. If it is an underglaze you are looking for are you planning on using a glaze overtop of it or are you looking for a vitreous slip? Also, you are using a clay that fires to 1150C (very approx cone 3)?

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