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David Woodin

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Everything posted by David Woodin

  1. There is another way to find out if your glaze has the right consistency and that is to use a spatula, stir the glaze and then at about a 30 deg angle let the glaze roll off and count the drips. So if it runs off like water it is too thin, if it runs off than drips about 6 to 7 drips, at least for me it is fine. Yes the consistency will change as you are glazing pots. David
  2. You could use a 6 cup and tile blend of A base glaze and B base glaze plus 5% stain. 150 grams base for A and 150 grams base plus 5% stain for B Use a syringe , 1 50cc A, 2 40cc A 10cc B,3 30cc A 20ccB, 4 20cc A 30cc B, 5 10cc A 40cc B. 6 50cc B

    1. Joseph Fireborn

      Joseph Fireborn

      Thanks, I will think about this. I am not sure I directly understand it I need to write it down on paper.

  3. I use containers 1 quart from home depot for the 4 corners. The individual cups are used yogurt cups about 6 oz. The test tile, because I am interested in vertical tests are extruded test tiles long enough to make 5 tests per tile times 7 tiles for the 35 grid. I only use 300 gram batch for the corners. The syringe is 60 cc McKesson Syringe without needle order 102-SC60C20. Each cup has 48 Milli Litres per sample. David
  4. I agree that the Currie method is a great teaching and testing tool. Unfortunately if a glaze is not within the cone 6 food safe limits for alumina and silica then the 35 Currie grid also won't have any glazes within the limits but some may look good. You can customize the Currie grid or can get great results with a custom 20 grid. This involves keeping the corners within the limits. David
  5. The top temperature for a 60 ramp rate will now be around 2218 F minus 200 deg = 2018 F. Orton cone tables are for the last 200 deg F of the firing. The 5 minute hold is to give the kiln a chance to level out the temperature before starting the final ramp. You can stay with 1982 but all that does is make for a longer total firing firing. You can play around with the hold if you want. As for a hold at the end of the firing I usually start with a 3 minute hold and add to it if necessary. If you are refiring ware than you may want to go slower on the second ramp, especially if refirng plates, 350F works for me. David
  6. You don't need a hold and can enter 0 instead. I would enter a temperature for ramp 2 of 2018 and a hold of 0.05 minutes. You don't need ERCD on, if it is on and the elements are lagging behind temperature it can shut the kiln off. Make sure you press review program and ramp 3 says 80 cone 6, before starting the kiln. Also since this is your first time try to be around for ramp 3 , and make sure it is ramping up at 80 deg by pressing the review seg button. After the firing hit review and it will show the final temperature. If the cones don't show quite enough heat work than you can play with a hold for ramp 3. You should not need any more than a five minute hold. David
  7. The alumina value is on the border line and the Al/SI ratio of 7.3 isn't going to give a good translucent glaze. According to Michael Bailey "glazes cone 6" the best clear glazes are around a Al/SI ratio of 9.1 to 14.05. A Currie grid might reveal some glazes at cone 6. But it would be easier to take a cone 6 clear glaze that is close to AL/SI 9 and run a Currie grid on it. David
  8. I sent an email with the food safe limits, Hesselberth & Ron Roy. I am using Matrix glaze program. There is also another book by Michael Bailey "Glazes Cone 6" which has a section on transparent glazes. I am assuming you have a glaze program, if not I could put in the recipes in Matrix and email you a formula of the glaze for cone 6 . This could save you time before firing a lot of unknown glazes. David
  9. There is very good information on clear glazes in John Britt's "Mid range Glazes" The glaze you are thinking of working with is not in the food safe limits. David
  10. There is a preface to his book "Pottery Form" that may be of interest. I know of the head forms but this was after he went to Japan and I was no longer a student of his. I will ask my friend Prof. Wally Higgins about this. David
  11. Daniel Rhodes was a kind and respected teacher, I was luckily to be one of his students, before his books appeared. Another of his excellent books is "Pottery Form" David
  12. I think you could help the pin holing problem by changing your last ramp to cone 6. Instead of 120 F ramp go to 80 F ramp than go to cone table and hit cone 6. The controller will then calculate the temperature required to go at a 80 deg F ramp to cone 6. You may also find that with this slower ramp you don't need the cool down. The final temperature will now be around 2218 F instead of 2232 F. You can verify this after the firing by hitting the review button. If you review the program before firing it will say 80 F ramp cone 6 David
  13. I have never used the 27 F ramp, because of the time it takes. I do use sometimes the 60 F , and the 80 F ramp and make my own program to keep the overall time around 7 hours. David
  14. You can use a hold at cone 6 but you have to change the top temperature to keep a cone 6 firing . For example cone 6 at 108 F ramp equals 2230 F, no hold, but a 30 minute hold means you need to change the top temperature by -40 = 2190 F to get the cone 6 to stay about the same. David
  15. A slower firing will give you improved results. You should fire to 1965 deg F than change ramp to 27 deg F and fire to 2165 deg F, and use self supporting cones. The cone tables are based on the last 200 deg F of firing. You can also use different rates for the last 200 deg F, example 60 deg ramp to 2205 deg F starting at 2005 deg F. Depending on how good your thermocouple is you should come close to cone 6 down. You can also change how fast you get to the 200 deg F before changing the final ramp to temperature so that it will not take such a long total time to fire the kiln. David
  16. Just replace the wires on the terminal board just the way they came off. I wouldn't add any solder to the wires, this will add another dissimilar metal and could introduce unwanted errors in the the readings. You will just do fine replacing the thermocouple your self. David
  17. You should be able to control gas manually by placing the controller in manual mode which then reads the output to the gas valve. If you don't want to use the auto gas valve then there should also be a hand lever valve near the gas pressure gage. In that case with the hand valve shut off, put the controller on Manual, set to 100% output than you can slowly open the hand lever valve to get any gas pressure you want. If you have damper control than you will have to put that controller on manual, or disconnect the linkage and move the damper to where you want it. David
  18. Hi Mark, If the original post was to fully automate a kiln including oxidation and reduction, than I read it wrong , because this becomes a very complicated thing to do. Also what kind of burners, venturi or forced air. As I posted earlier I only use automatic to get up to the body reduction, then I go to manual, which involves gas, air and damper adjustments. Industry usually doesn't want to go into reduction so automatic control is what they use. There should be an easy way to use any kiln in the manual mode if that is want the customer wants. David
  19. Alpine kilns are rugged and well made kilns, usually found at University's or production potters. The only one I worked on was a larger kiln and had a minor problem with a gas valve. They have a web site www.alpinekilns.com David
  20. You might want to look into the jiggering method. David
  21. Here is a base recipe that works at cone 8 down to cone 9 -15%. You will have to experiment with colorants. The 3 hour soak range is from 2000 Deg F to 1980 deg F. Allthough porcelain may be the preferred clay I use my stoneware clay and am pleased with the results. The size and amount of crystals vary with vertical or horizontal surfaces. Frit 3110 53.6 Calcined zinc Oxide 26.7 Silica 19.7 David
  22. I am sorry, I thought you were trying for 1/2 more than cone 6 when actually you wanted cone 6 @ 45deg So you are within 3 deg F of 45 deg. the calculation comes from Orton Cone Calculation program. I am glad you use the self standing cones. David
  23. I am curious about firing to 2165 F with a 50 min hold. Even with this hold you will only get to about 2217 F which is less than cone 6 at a 108 F ramp. I am missing something? David
  24. I use the controller to easily get to the body reduction temperature at any rate of rise I want with no risk of going too fast or slow or reducing instead of oxidizing. From then on it is hands on control of the firing. David
  25. When cutting off the amount of clay needed for the jiggering, I take a wood mallet and pound the clay down, than finish the slab by running it though a slab roller for the final thickness. Than place the slab on the jigger mold and starting from the center push it down on the mold with the wheel spinning. Your molds should not be so wet that you can't get more than 2 a day, which means you must not be using the correct ratio. I have 12 molds for plates and can get two a day easily from each mold. The plates shouldn't be forced off the molds they will lift themselves off. If needed you can pop them off with about 20 psi of air presssure. Were the plates your design? David
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