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martinkohout

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About martinkohout

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    Berlin, Germany
  1. Hi Martin, The clay I use says cone 10, I fire to cone 9 down with cone ten starting in a gas kiln. I use the same clay for electric kiln firing and fire it at cone 7 and the clay doesn't leak water at cone 7 but will leak at cone 5 and 6. This will not help solve the blistering problem you now have which could be caused by the bisque firing program, not taking enough time between 1000 deg F and 1200 deg F, which will help burn out all the organic material. David Ok! I will ask at the workshop, how they have the bisque firing set up. The bisque is done the same for everyone working there and the second firing is the only one I can set myself.
  2. How thick do you apply the glaze, any binders or suspension materials? The clay fires from cone 5.5 to 9. you are firing at the low end. Fill one of your test pieces with water and place it on a napkin look at it the next day, it may leak at the temperature you fire to. It has a high water absorption even at cone 9. Does any glaze fit properly? David Hello David, I will test that! Since I'm really new to pottery, how do I generally find out the ideal firing range for clay body? They only inform about the max temperature in the shop...
  3. Here are actually few results with the first test glazes we did with my friend and applied on our very first pots. We actually like the coral looking results on the outside, but we definitely need to get some good liner and more knowledge about why the glazes came out this way to work the way we want...
  4. Hello David, I have to say I'm really amazed by all the great help and care in this forum (which I registered to just recently). I will definitely try the recipe you posted and let you know how it went. I can confirm the glaze is dry on white clay pots and I wasn't sure whether it wasn't somehow relating to the firing programme. I live in Germany, but I recently got 3134 and 3110 so I will be able to work with few glazes I wasn't able to mix with mostly american recipes. Have a great day!
  5. If you skipped step1, this meant the kiln went as fast as it can to step 2. That would not be a good idea as the kiln could have been going at 500 deg per hour or more and anything could have happened to the glaze as it tried to adhere to the pot. I am wrong as to what I said about this glaze. It does have a lot of flux and doesn't fit in cone 6 limits. I fired it using EPK instead of OM4 ball clay to cone 06, it was a very dry white surface no blemishes, than fired to cone 4 still a dry white surface, then to cone 6 still white but not quite as dry a surface, cone 8 still dry off white matte. Please post the firing schedule used. David Hello David, the 1st step in our schedule is identical with the second one in the linked schedule, so we start from 0 and go with 166°C/hr to 945... Do you think that's too fast then? I'm sure it won't take too much more energy if we drop it slower, but again, it's a wild guess for me in terms of how much to drop it. Thank you! M
  6. Dear David, thank you for the recipe! Would you happen to have a picture of it?
  7. This glaze doesn't come close to cone 6 limits and probably is boiling, hence the cratering. Try it on a pot you are bisquing and see what happens, in other words it is like a cone 04 glaze with the amount of flux it has. David Hello David, thank you for the comment. I will give that test you mention a try if they allow me where we are firing. Strange than, that the author writes it's for cone 6 to 8
  8. or maybe being able to do the first step in the programme linked? although the temperature is very low for that maybe 1 55°C/hr to 104 100 220 60min 2:27
  9. haha, thanks. it's sort of in a good direction towards our goal, but to make it better, i want to understand the causes etc
  10. thank you everyone for the notes! i will try to extend the firing for 10 min, thinner glaze application and later also another clay
  11. hello. for example the first image shows this recipe: https://www.flickr.com/photos/glazes/1085548412/in/album-72157602049172454/ WoDo 40/10 ^6-8 Ox. Recipe Name: WoDo 40/10 Cone: 6-8 Color: Firing: Surface: Matte Amount Ingredient 40 Nepheline Syenite 10 Talc 6 Wollastonite 25 Dolomite 20 Ball Clay--Old Mine #4 101 Total
  12. just as a side note. in one of the texts i was looking at, they say that for pinhole troubleshoot, i could hold the temperature for maturing for up to 2hrs, does that mean the top temperature of 1190? 7. hold the kiln at the glaze maturing temperature for a soaking period of up to two hours http://ceramicartsdaily.org/ceramic-glaze-recipes/glaze-chemistry-ceramic-glaze-recipes-2/how-to-correct-five-common-ceramic-glaze-defects/
  13. hello bciske! thank you for the fast reaction. the schedule is as follows: 166°C/hr to 945 300 1733 0 7:29 60°C/hr to 1190 108 2175 15min 11:50 then kiln off the clay is this in the attached picture unfortunately i don't know the specs of bisque since we work in a shared workshop any idea whether it makes more sense to have the kiln cooling off with a fixed temperature (150F/Hr) and no hold (limitation of the kiln computer) than just switching it off? from what i have read it shall be better with a longer cooling, but most of the time people mention the hold in the cooling, which I can do, so I wonder whether the temperature for cooling shall be even lower to balance this a bit thank you!
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