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About DBPottery

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  • Location
    Tampa, FL
  • Interests
    Cone 5/6 Stoneware, Wheel Throwing

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  1. I certainly agree testing the finished glaze is the best way to go. I just wasn't sure if at such a small amount that it can be considered an impurity and be ignored. Officially leach testing isn't exactly cheap. Thanks.
  2. Sorry, I should have worded that better. The specific analysis just for the cobalt carbonate analysis shows lead in the amount of 0.0002% in the cobalt carbonate. The Red Iron Oxide analysis shows lead at 30ppm in the analysis of just the Red Iron oxide. I was trying to point out the amount of lead in each material. I know some toxic metals are just natural impurities, but wasn't sure at what point it needs tested for, as the main material is the core of the chemical makeup. Thank you, Daniel
  3. Bump, looking for opinions. Thanks, Daniel
  4. Hello, Some of the material analysis I received show trace amounts of a toxic material. I'll specifically point out lead. I only recall seeing it in the colorants, such as Cobalt (0.0002%) and Red Iron Oxide (30ppm). At such a small amount, is this something I should leach test for? I want to be on the safe side, but it just seems like an impurity than can be ignored. Looking to see what is standard protocol for this situation. Thanks, Daniel
  5. Thanks for the replies. I feel much more confident moving forward now. Hoping for the best, but I know a lot of testing is to be had.
  6. I'm now starting to get into making my own Cone 6 glazes. I've had enough issues with commercial glazes sold for cone 5/6, and even more so now that I've been convinced I need to fire my clay to Cone 6 (originally I was told to do cone 5, but for vitrification purposes, Cone 6 is needed). I'm based in Tampa, FL. Ideally trying to get my raw materials locally vs. shipped in. I see plenty of places to buy the raw materials. I just seem to be hitting some road blocks when requesting a materials analysis. I've been using Hessberth's and Roy's Mastering Cone 6 Glazes and John Britt's Mid-Range Glazes book for guidance. Additionally, I'm using the Glaze Master software to help make some conversions for materials now unavailable. Based on these, I've been convinced a good materials analysis is necessary. How much is it worth fussing over a good materials analysis? For example, one supplier lists a "typical analysis" on their website and Glaze Master has some pre-populated. I get the feeling I might have received some old analysis docs from one supplier, rather than the current lot #. Most of the analysis docs I've received, are close to what is already in Glaze Master (with 1% or less), so I'm thinking I might be fussing over it a little too much, but need some opinions. Any recommend suppliers? Thanks in advance.
  7. Thanks for the replies. I am making some progress on the firings. My last firing came out pretty good. Basically once the kiln got to 2000 degrees I pretty much decided to baby sit it. From 2000 till finish I would put all switches on high for 5-10 min then switch it it back down to top on med and bottom on high for 20-30 minutes. Yes, it's a lot of work, but that's really the only way for me to slow down the last part of the firing. Then, once the cone tripped the kiln sitter I turned the kiln back on for 20 minutes on med/high. Needless to say I'm counting the days until I can get a digital kiln to do this all for me. If I wasn't moving in the next year I would probably just have gotten one by now. My method allowed me to eliminate all the bubbles on the light blue glaze I posted a picture of above. Thanks for the complements on the glazes. Yes, that clay is a stoneware with manganese flecks. It's Highwater's Speckled Brownstone. Something I just found though is that many of my glaze imperfections seem to be with clays that have the manganese flecks. I started looking around at all my work that is stoneware with no manganese flecks and the glazes are much smoother. The manganese flecks seem to be causing many pin holes where the speck is and with matt glazes they have pin holes in general. Do the manganese flecks outgas a lot more or something? ​I do have a question about the bisque firings. I have looked more into theories behind how to properly bisque fire since that was suggested that it may be part of the problem and got some good insight to test on my next round of bisque firing. I was wondering how tight everyone packs their kiln for a bisque firing? From what I have read on this forum and other places I think I may be packing my kiln too tight. For example I would stack 3-5 plates on top of each other and put 1-2 smaller bowls inside a larger bowl. Should I really be making sure all pieces are placed in the kiln separately? Thanks again, Daniel
  8. DBPottery

    Old Potters Wheel Is New Again.

    Nice work! I wish I could have even found a used potters wheel when I first started. I gave in and just spent what I had to. I wouldn't have cared if I had to put a little work into it to get it working if I did find one used.
  9. Thanks for the replies. In the end, I'm just trying to get rid of the bubbles. I'm not saying that my bisque firing doesn't have anything to do with it, but I never got bubbles with these glazes before prior to the element change. Denice, I have that Skutt Pyrometer too! I love it. I have always thought of getting a second thermocouple for it. I have attached some pics of the bubbles. I tried the best I could to get a picture of them but some things are just hard to see in pics. Daniel
  10. DBPottery

    Best Time To Buy A Wheel?

    I agree about Bennett Pottery! That is where I bought my Brent wheel from 10 yrs ago and I saved hundreds compared to other stores. However, I would certainly shop around.
  11. Thanks again for the help! I just got the kiln back from getting the elements replaced a few weeks ago and that was most certainly the issue. Using my normal firing schedule I had been using it got to cone 5 in 4 hrs 35 min on the first shot. That firing schedule is pretty aggressive so I slowed it down by giving low and medium a few more hours of time before going to high and that got me to cone 5 in just short of 10 hours on the second shot. I just wish I could figure out a good way to cool this manual kiln down a bit slower. I think that the fast cool down is causing the glazes to have a few more bubbles now. I'm pretty sure that the bubbles had plenty of time to smooth out before the elements got changed because it took sooooooo long to get to a cone 5/6. Now this is where a digital firing kiln could really come in to help me out. At least now I can do some trial and error more easily because the kiln isn't sweating to get up to cone 5/6. Daniel
  12. I just checked again to be sure, all the elements do glow. I'm going to take it over to the kiln repair shop soon and see what he thinks. Thanks again for the help! Daniel
  13. Thanks for the replies so far. I'm not sure how to answer your question because I have nothing to compare the elements to. I have attached a picture if that helps. Daniel
  14. Yes, it is rated to 2300 degrees so it's good for cone 5/6.
  15. Hello everyone! I can across this forum through some Google searching and it had some good information so I thought I would join. I throw stoneware and fire to cone 5/6 fire for my glazes. I started with clay at age 8 and starting throwing at age 12. Now being 22 I've been at it for a while (whenever free time allows). Anyways, to set the background to the question, I have an old manual Jen Kens kiln I got used 12 years ago. We were not sure how old it was when we bought it but after having the local kiln repair guy replace a bad switch 3 months ago he mentioned the kiln was at least 30 years old and in great condition because it didn't appear used much for its age. I talked with him about knowing when it was time to replace the elements. I've never replaced them since I owned the kiln and I have no idea when the previous owner replaced them because he had past away and it was his family selling the kiln. I have fired this kiln at least 125 (probably more) times since I have owned it (first 3 years cone 06-04, last 9 years 04/05 bisque and cone 5 for glaze). This is my first kiln so I have no other kiln to compare firing times to, to tell if the firing times were too long to begin with. So I wanted to get an idea of what others firing times are for certain cones. I know it depends on many factors but I wanted to get a basis. My kiln (approximately- my kiln usually varies .5 hours to and hour depending on load size): Cone 04/05 7.5-9 hours Cone 5 14-16 hours (on average- one load took 12 hours and had one load take up to 18 hours) Recently I have been monitoring this kiln more with the pyrometer. The kiln gets to 2000 degrees in decent time (in my opinion), but it seems the last 150 degrees are taking longer than it should be to get to a cone 5. The last 150 degrees it is at least 5-6 hours of the firing. Thank you in advance, Daniel

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