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Dave K

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  1. Min, I am not 100% sure. The EPK is use all of the time in making glaze so I am pretty sure it is okay. The alumina hydrate I am less sure of. I have had it for several years and only use it for kiln wash. I will replace it and try again. Is the a general rule on how often the strip and recoat the shelves? The glaze that ran was a commercial cone 5 and I am firing at a hard cone 6 because of vitrification problems with my clay. I assume it was over fired thus causing it to run, however, if the kiln wash was doing it's job shouldn't cylinder easily come off of the shelf? Thank you for the help.
  2. I am using a recipe for kiln wash that is 50% alumina hydrate, 25% EPK, and 25% calcined EPK about the thickness whole milk. I usually apply 2 coats by brush or 3 by roller. It seem like after 2 or 3 glaze firings any runs do not release from the shelf. I just had a cylinder that the glaze ran pretty badly and in trying to remove it from the shelf most of the bottom of the cylinder broke off and I had to use a hammer and chisel to get the pieces off. Do I need to strip and recoat the shelves after every glaze firing ( I hope not) or am I doing something wrong?
  3. What is an acceptable percentage on the absorption test especially on a test bar that is 1/2 inch thick? I know Standard rates the 563 at 1%, but I don't know how they arrive at that.
  4. Thanks for the reply Neil. I will change my firing schedule. With dropping the .10 hold ,going back to 150 and trying for a little hotter. What temp would you recommend? The thought of the pieces being too thick is a real possibility. I once had a problem with the bottoms cracking because they were too thick. I make an effort to make sure the bottoms and lower part of the vases are no more than 1/2 inch thick and hopefully like 3/8 inch. That being said I am pretty new to pottery so anything is possible. As far as the clay being from the same batch, maybe. The dates on the boxes are the same but what be a batch number can vary. At my supplier that batch number are rarely the same on any given palate of clay. Would you explain what a test bar is and how to test absorption? This has all been very helpful. Thanks again, Dave
  5. I use Standard 563 stoneware and fire to cone 6. My firing schedule is 60 200 2.0 200 250 0 400 1978 0 100 2185 .10 My kiln fires hotter by about 35 degrees. The self standing pryrometric cones are almost touching the kiln shelf or base they are on, so to me a little over fired. Two firings ago I changed the last ramp rate to 150 from 100 . The vases all leaked water when I tested them. The pyrometric cones indicated a very slight under fire but only by a hair. The prior firing at 100 everything seem fine. Last firing I changed it back to 100 and re-fire the ones that leaked along with 3 new ones. The re-fired ones are fine and don't leak now but the 3 new ones leak. They were all on the top shelf in no particular order. My kiln indicated a power failure on the bisque fire of the 3 new ones but the 04 pyrometric cones had just started to move so I didn't redo it. Any thoughts as to what my problem is? Thanks, Dave
  6. I picked up some 563 and tried it this afternoon. It was a little soft but easy to throw. I will see how it fires. I will also check with my supplier to see if they have 630, if not I will have them order some and give it a try. Min, I have an L&L kiln with 3 thermocouples and it's pretty much the same on all levels at cone 6 but not at cone 04. Is there any "wiggle room" for a cone 6 clay to be fully vitrified? If the pyrometric cone is at 2:00 is that close enough and if not am I better off bumping the hold time up a little and risk being over fired? Are you saying that if the absorption rate is high enough that a vitrified piece will leak? Thanks to everyone for the suggestions and help.
  7. Thanks for the replies. Nerd, I think it is point #3 that is my problem. I will try not to make this too long. I use Standard Ceramics clay and have been making vases with 182 which is cone 6-10. My wife put flowers in one and it ended up leaking. Upon testing more of my vases I found that they almost all leak. Doing some research I find that 182 is not vitrified at cone 6 and that glaze will not usually prevent leaking. It makes me wonder what good is a cone 6-10 clay. I am in the process of changing to a different clay body that is a true cone 6 clay. In looking at various ones Standard has to offer I see the absorption rating and wondered what it actually means in the overall picture of making vases. I also tried 365 and 213 porcelain. The 365 did not leak but the 213 did, and they are both rated at cone 6. They were both fired to a cone 6 by the pyrometric cones. It leaves me more than a little confused.
  8. Would someone explain absorption in relation to clay. I use stoneware and porcelain and fire to cone 6. Any information and advice about how it effects to pottery making process would be appreciated. Thanks.
  9. I have fired fine copper wire wrapped around a vase at cone 6 oxidation and also very small pieces of bronze and brass. For me the results were not interesting enough to try it again.
  10. I am interested is getting a commerical spray booth. I am looking at a Laguna Pro-X. It's size looks about right for my space. I can't find any reviews on it. Does anyone have one or know someone who does? I would appreciate any input on spray booths in general. It is a big investment and would like to have as much info on them as possible.
  11. What do you mean by " legs"? How much clay should be necessary for a 12" cylinder with 4 1/2" to 5" base and pretty much straight up and down? I use stoneware and for the first time achieved 12" with 7 pounds of clay. I was pleased but suspect that is too heavy.
  12. I am going to go with the EZE spray gun. Thanks to everyone for your help.
  13. With the EZE spray gun is the spray pattern adjustable? Will it spray most glazes without thinning?
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