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  2. I am with @liambesaw in that there is virtually no difference. My issue with all the lowfire Orton cones is they don’t tend to bend in a picture perfect fashion. They tend to bend mostly at the hips which I believe is the result of the cross section and saving some material but just speculation there. Here is another point to ponder, radiation! At the end of your firing most of the heat will be by radiation, then conduction, then very little by convection.. Why is that relevant? Because if either of your cones has more of a clear vision or line of sight to your elements they will absorb more heat energy. Could be the difference in bend from cone to cone in your picture. Two cones next to each other but one being able to see more glowing elements. Lastly cones are made of glaze that would melt just like glaze at about 6 cones higher temperature. Their formulation is pretty established and consistent so they last a long time with the exception of if they get wet or contaminated usually with a wet substance. An 04 Cone is - 0.3:0.7 flux ratio, 0.2 iron, 0.3 Alumina, 0.2 Boron, 3.8 silica hey, it’s a glaze!
  3. Today
  4. I mean the difference between those two cones could be as little as 10-20 degrees. One is slightly underfired and the other is slightly overfired. You need to get another defective box so you can have one that is right between them.
  5. Mark, thanks for answering. I wish I could attribute it to spacing, but the cones were right next to each other, maybe about a 1/4" apart. None of the pieces being fired were close to them. I'm quite sure that when the cones didn't bend fully in my test kiln, they came from one box, and when they bent fully, they came from the other. They've never gotten wet. In the end, it probably doesn't matter that much if I'm achieving exactly ^04, but the dilemma is not knowing which one to believe. It's like finding two different so-called 12" rulers that are different sizes. An additional "proof" that something is wrong with at least one these boxes is that I get consistent results at other temperatures with other cones. My larger kiln will be more affected by load size, but the test kiln is so very tiny that I can't imagine there's much of a difference in temperature from one spot to another.
  6. Yesterday
  7. Gen: Gold specks possible pyrite: but not mica- mica would be glassy or white. Pyrite is FeS (sulfur) and judging by your result with 50 local 50 B-mix: you have in excess of 8% iron content. The only issue that makes me doubt pyrite is the dried greenish color: hematite in the presence of calcium will present greenish. The simple test to determine that: iron disulfide (pyrite) will go brown at cone 6- hematite will keep a deep red tint. Alluvial soil is fine grained- sub micron and lower in alumina. If pyrite, doubt you can fire past cone 1-2 without pyroplastic issues. If hematite: then it should handle cone 6 because hematite and magnetite clay runs between 20-24% alumina- iron disulfide runs 15-17%. The test is simple: just put a button of you clay on a tile, scrap whatever and cook it to cone 6. Brown- iron disulfide- low fire. Deep red- hematite. Plasticity- your sample has high sand content which is "tempering" the clay- not the same as plasticity. Tempering comes from the brick industry- used to produce malleability, but not plasticity. (They do not want high shrink values). Plasticity- start with 20% OM4. EX. 200 grams OM4 per 1000 grams local clay. You are hand mixing I assume? If so, it will take 3-5 days before full plasticity will develop. Overdo the plasticizer then you will have the opposite problem of clay fatigue- slumping-folding. Burn a sample to cone 6- confirm what the iron source is: then address formula- cone value. Nerd
  8. Cone 6 stoneware 76% OM4, 14% feldspar, 10% silica. ( This is a plasticity fix only.)
  9. Would this work for cone 6 midrange stoneware? Or is it strictly for high fire?
  10. Denice, I also recycle my clay. First because I live in the city, and would not know or want to dump clay anywhere. Second because I believe it is a resource, and try to use it. Happy to know someone out there has the patience for coil pottery, and uses colored clays to enhance it. best, Pres
  11. I agree with Callie. The costs will be specific to your operation because of differences in rent, utilities, and what you're able to charge per student. It's just going to be a matter of crunching the numbers there. I can tell you that the one thing my students really like, compared to other studios, is that once they've paid for an 8 week session, there aren't a bunch of little fees that nickel and dime them to death. Tuition charge cover open studio time, too. Clay prices include glazing and firing. If you want them to keep coming back, don't make them feel like it costs them every time they walk in. It's also a lot easier for me as the owner to not have to be dealing with the money all the time.
  12. Cones do not go bad or age out . I have used cones that are 40 years old with great success . The oly issue is if thay ever got wet-then they can go bad.meaning weird readings. My guess is the two cones you show where in slighly different areas which you will fine evne in that tiny kiln will have different temps all over it.The cone shoes the time temperature heat work that happens in that given spot you place it. 100% of the time it's not the cone but the kiln that is differnt temps. Since you are using the same program the other thing that changes is the load -that is whats different every time and the cones will show that as well as it effects temp as well.
  13. I've been getting very inconsistent results in a new, little test kiln at ^04. Using exactly the same program with almost identical loads, my witness cone would sometimes bend close to the shelf and sometimes not bend much at all. It dawned on me that I was pulling the cones from two different boxes, so decided to test the cones themselves the other day in my larger kiln. I placed them right next to each other, and you can see the result in the attached image. I've contacted Orton about it, but have yet to receive a response. Both boxes are clearly labeled as ^04 cones, and the cones themselves are similarly marked. I can't think of any other explanation other than one of the boxes contains defective cones. But which one?? One of the boxes is older than the other, but I don't remember which one's which. Do these things have an expiration date?! Anyone else ever encounter something like this?
  14. I (and several others in the college studio) have added red iron oxide (RIO) into a commercial clay by sprinkling red iron oxide on the clay in thin layers combined with the Stack and slam wire edging technique of Michael Wendt. see his youtube video: A little iron will make a BIG change in the surface appearance of the clay. As I remember I used a something like a big salt shaker to sprinkle the RIO on the clay. check the iron content of Red Art clay and use that as a maximum level to add to the commercial clay. LT
  15. Thank you for the links! I looked for similar topics here but sometimes if you don't use the right key word it doesn't come up. I did drop a piece of the fired clay into vinegar and it only fizzed for a second, so I'm interpreting that to mean I'm good on lime distribution. I am working on more test tiles today, and buying more witness cones for the varying temps I plan to test at. I think analysis will also help in that I should be focusing on practicing with what I have rather than playing with a theory. But I love learning new things. So much appreciation for the wisdom and guidance!
  16. I agree. Don't just add red iron oxide. It tends to make the body more brittle and doesn't disperse well. You're better off adding a red clay. Any red clay can work- Redart, Newman, etc. See what your local clay supplier has in stock.
  17. @GreyBird dug clay along the Hudson River and had a sample analyzed, you could message her and ask where she got it done. This is the thread showing the process etc. for GreyBirds found clay. There is also a lot of good info in that thread from @glazenerd . Found clay is often earthenware type clay so adding the ^10 B-mix would definitely raise the maturation temperature but it doesn't necessarily mean the clay would be okay with just that addition. Assuming what you have is a lowfire red clay then by adding the ^10 clay is in effect no different than when RedArt (lowfire red clay) is added to bodies to introduce iron into them, still have to balance the recipe out. Have a look at the recipes in the Grinding Room from Alfred. Some of the materials used are no longer available but it will give you an idea of what you might need to add to your clay to complete it. It's going to be a process of trial and error but if you get an analysis done it will make the job a lot easier.
  18. Thank you, I got lucky with the glaze breaks.
  19. I think the trick to your situation will be to get very specific. A lot of any business numbers will depend to a degree on how you want to structure the business, and what you plan to offer as services/facilities. How much of a business plan have you built so far?
  20. Testing makes a lot of sense. Do you have a suggested lab?
  21. In college there was one clay body we could mix that had an addition of 3.5% red iron oxide. Cleanup after throwing with the stuff looked like a murder cover up, and it easily contaminated anything in the studio. It fired to a beautiful dark purplish brown colour at cone ten, particularly in any kind of atmospheric kiln. It did not take glaze at all well. To get the iron into the clay, you had to add it to the water in the Soldner mixer before adding the other ingredients, or you wouldn't get even distribution. I think adding it to a pug mill wouldn't get the iron incorporated thoroughly enough. I am also unsure of what the exact effect of adding a flux like iron to a clay body would be. Bloating, if too much, maybe? I second Min's recommendation about adding an iron bearing clay. Red Art might work if you can't get the Redstone.
  22. It would be better to use a high iron clay rather than RIO. If you can get hold of some Redstone clay from Plainsman that would be a terrific choice. It's a deep red at cone 6, is plastic, and vitrifies at about cone 7. Redstone ( @liaemars9 I'm going to change the title of this thread to better reflect the question you are asking)
  23. My studio is full of clay right now, I have a off white speckled, Speckled buff. Standard red, Death Valley red and yellow. These are my clay's used for coiling , the coils are smoothed and Indian designs usually Mimbres or Anazai are applied using stains or glazes. At least half of the pot is not glazed so the color of the clay and texture is important. I also have a buff throwing clay that I have been using to improve my throwing skills. I recycle my clay, it is part of my process. I went to college during the hippie era and was taught that all of mother earths offerings such as clay are precious and need to be recycled. I was also taught to evaluate a piece before you fire it, think about someone finding that pot hundreds of years from now. Is it worthy of being around that long, because it is fired it won't disintegrate and return to the earth. Denice
  24. Just wanted to put this reminder here for those wishing to post in the Marketplace. You must be a registered user to post in the Community Marketplace, or anywhere else on the forum! Thanks, Jennifer
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