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Bill Kielb

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Everything posted by Bill Kielb

  1. No solution for this one but the combination of clay, slip, glaze does not fit so I would test first next time. You might want to test out finish firing to 04 as well to see if that makes the clay and glaze combination behave better.
  2. Almost looks like there are more than one relay for the bottom elements or the relay for the bottom is simply not firing on call, hence the early 100% Call with no significant heating.
  3. Nice crackle, save that recipe! I think I looked at this base with your initial ingredients and location in Stull and entered the following to try attempting to get about a 0.2:0.8 R2O:RO and .54 - .56 alumina and keep your boron at about 0.15 for cone 6. With mostly your materials calcined kaolin - 26.79 3124 - 25.00 silica 9 -> 19. = matte -> Gloss.. dolomite - 8 talc - 12 wollastonite - 4 neph sy. - 20 Thats as much as I messed with this, I needed neph sy for the alumina but the more neph sy the more sodium which likely becomes a crazing issue. Anyway, your current recipe is so different than the earlier, I don’t think these choices apply anymore. Some real good content here about glazes …. And it’s free https://suemcleodceramics.com/understanding-cone-6-nceca-presentation-2018/ lots of things from boron to crazing, it’s definitely a good read I would recommend.
  4. More silica will make it smoother but not likely solve the crackle (crazing) which is a glaze fit issue or difference in the coefficient of expansion. COE problems can be tough to solve especially for a matte. Moving the R2O more towards 0.2 while maintaining the relatively high alumina can be a successful technique. Unless you are committed to this recipe for some reason, as Neil said it may be easier just to find one that already works on Glazy or from another source. If you are doing this as part of a learning experience then that is admirable. Here is a nice video that Sue McLeod presented at NCECA a few years back. https://youtu.be/Uf07jOKuW5s it has a lot of Stull and surface indication but near the very end she discusses the reason this technique can work for mattes which really is removing or reducing higher expansion fluxes for lower expansion ones. Glaze chemistry is fairly complex and folks spend many years learning the nuances. Raising the silica will generally transform the glaze from matte (approximately) 5:1 Si:Al to glossy (Approximately) 7:1 Si:Al so along the way the matte becomes more buttery or glossy. Solve the fit problem first, then you can work on the texture pretty easily.. Here is a matte you can try https://glazy.org/recipes/19734 some have great results (four stars) and others hate it with passion. No guarantees but if it fits your clay now you know that by simply adding silica to this it can go from matte to gloss, rough to buttery, metal marking to non metal marking. The more you can learn the more you can solve.
  5. The only thing I can remotely think of is to remove any residue or oils from the thermocouple. One could do that by wiping it off or torching it to 1000 degrees for a few seconds. I would be curious as to the reasoning ….. as thermocouples oxidize themselves to death by their function. Covering them often improves lifespan a bit. I really would love to know why the person who told you that did so, and what longevity they would attribute to that procedure. Then I guess I would form an opinion on credibility from that. I would love to know the why if you ever get an explanation.
  6. This recipe appears to be by weight. So that would be a 100 gram recipe, to scale up to 200 grams,, multiply everything by 2 and so on. Do you have a scale to try a small batch by weighing everything?
  7. That’s often the unpredictable issue. Non PhD folks may find it counterintuitive to look at the bottom of the bowl before they use the top of it. Once out of your direct supervision and control, well ………. It’s just out of control. The label may be ineffective for the new user. Pretty common actually as wares are handed down, gifted or eventually sold.
  8. I think that is very likely the difference in COE was the cause. Looks like a sudden catastrophic material failure not necessarily following a common weakened path to relieve the stress. Nice Empty bowl, bowl BTW.
  9. Just asking, have you tried getting a new password? There was a intro popup on the new site for a bit and several comments to the effect here of renewing your login so to speak. Not for this forum though. Maybe that will help. BTW - intro still there “Also, because of the new account management system, you will need to reset your password on the new CAN site. You can do this through the log-in button in the upper right corner of the site, or through the link in the "New website: Please reset your password" message you will see throughout the site (see image). ”
  10. If it works with wares in it, then wrapping just the bottom of the kiln - say up to the level of your shelf with 1” or more of high temp insulation would improve the available power of the kiln a bit more and is fairly easy to do. While not the best fix, maybe a functional fix and finally your most bang for the buck would be insulating top and bottom. If you do the top, the lid will distort so not really a workable idea, and the problem with the bottom is you need high temp rigid insulation to set the kiln on so wrapping the bottom outside is probably easiest. This very well is likely to accelerate the degradation of the bottom band a bit though depending on moisture etc…. Best of luck. I can tell you that a few months back we had an engineering student building his own kiln which was significantly underpowered and after adding two layers of insulation he was firing fine. So anything is possible, is it worth the effort to you?
  11. Wow, none of these sound promising actually, sorry. Something to try - put a full shelf in the bottom supported on tall stilts or fire brick. Maybe 8” off the Floors and see If this thing fires to cone six. This will block some of the element radiation but is a simple thing to try as if this has a floor element. If it does fire to temp, then we probably have a creative way or two to make it a bit more efficient and at least in the short term somewhat useful.
  12. Yep, you are spot on, this is billed as a lowfire kiln by Paragon. To make this work, you would need approximately 15,000 + watts for this size kiln………. 15000 + w is tough to power in a residence ………..Still Thinking………. If we could shrink the kiln but keep all the elements ………… can the center section be removed without losing elements? Just thinking of alternatives.
  13. I use the automatic for most normal firing as I believe the default speeds are fine and special programmability for custom firings when there is a real reason to go a different speed. I must say I never use the fast schedules as they are a bit on the edge for even firings and the mix of wares that might exist in many kilns. Cone 5 with a fifteen minute hold is not really all that custom but I will use the combination when temperature sensitive glazes are present. I also never really use the fast schedules, too fast for me and tend to be uneven unless in the test kiln for which many of my glazes are just fine fast fired but it’s such a small kiln it fires even at high speed. I never really fast bisque as well, with the variety of clays, it’s just not worth being unsure everything is burned out. I will say a -40 degree offset seems very high to me though. It makes me wonder how much is due to the fast speed.
  14. Electronic controllers cannot switch high power loads on and off. Instead relays are used to switch the elements and the controller switches the relays on and off so controllers can be used with most any size kiln by using the right number of relays. So it should be entirely doable but will likely take some familiarity with such circuits and safe control of circuits using relays. On another subject though, cone 4 is a bit odd for a rating. A Paragon that draws 48 amps ought to be rated cone 8 minimum and the Cress that draws only 20 amps likely would be a cone 8 kiln. Maybe 10 if very small. So your situation seems a bit contradictory. Can you list the exact model numbers of each kiln? You will find the model on an equipment tag affixed to the kiln. Maybe just post a clear picture of each. Also, what do you usually fire to ……… cone 6 perhaps?
  15. The more the merrier, or the bigger the better. Turns out when looking at the requirements of a spray gun they are rated in the range of approximately 9-12 cfm say at an approximate pressure of 40 psi. When looking at compressor performance one might believe they can cover this requirement easily ……. But ……. Compressors are rated differently and mostly over rated by leaps and bounds compared to real world requirements. So even a 1 hp 10 gallon likely won’t keep up with constant spraying of two guns. Fortunately spraying glazes allows one to take a break so the compressor can keep up. So as big as you can afford would be my suggestion, else you may wait for the compressor to catch up. The only other thing I can think of is oil or oil less. Oil less would be best as far as contamination and maintenance. Lots of folks using 6 gallon hot dog compressors every day for single use glaze spraying. Pressure is not usually an issue as most compressors will easily produce more than 100 psi.
  16. Cones measure heat AND the effect of heat over time so the temperature on a thermocouple is not nearly as important in clay as: what cone did you make it to? One can fire to cone 5 with a forty minute hold and make it to cone 7 overfiring their cone 5 clay and glaze yet never exceeding 2167 degrees (1186C) . In this case the thermocouple was right but all my stuff slumped and was ruined.
  17. Yes it is ought to be just fine. Wax burns off at around 800 degree f so in the range of let’s say 450 degrees to maybe 850 degrees folks often smell the wax. Use a lot of wax, lots of smell. You should not see any signs of carbon as it will burn away in the rest of the firing. Any kiln vent will help this but downdraft vents are often not capable of removing the smell completely …… and they are not really designed to get all the wax smell. So a downdraft will help but not likely to capture all of the wax smell. The smell will however disappear above 800 degrees. As far as refiring, a simple general way to think of this would be: for a glaze firing, if you have not fired within 300-400 degrees of you finish temperature then you have not done much real heatwork. Silica and alumina don’t melt less than 3000 degrees so they need flux and enough kiln energy to help them melt earlier. Until your kiln reaches this melting temperature (often called a eutectic) not much is done in the way of useful work on the glaze. So refiring is generally just fine for most. Technically (Per the Orton cone chart) most of the relevant heatwork to maturity is done in the last 200 - 250 degrees of the firing. For bisque firing, generally it’s not a concern, just rebisque to your proper cone. Generally It’s ok to bisque more than once and often done when multiple layers of decoration are desired.
  18. Maybe one of these or search ready to paint ceramic Santa’s https://www.thereadytopaintceramicshop.com/santas1.html
  19. While not a stain solution, definitely something to consider is lowfire glaze brushed over your finished project. Stroke and coat glaze is popular for this use. The piece is finish fired, then decorated with Stroke and Coat and down fired to cone 04. The mug bellow was down fired several times as the dragon was applied and took shape. Anyway not a stain solution but a way to apply reasonably durable color decoration to a finished item. The finish is a glossy hard glaze. Might give you ideas of your own.
  20. It’s better, not sure it will work as intended but if you are developing, and you believe it is what you want to try. The alumina is fairly high but it is a matte and ought to be in the 5:1 range. If it fits and you like it then adding silica ( small progressive increments) ought make it less matte. Probably can rid yourself of the calcined kaolin at this point, just a hassle to prepare and at 18% China clay, plenty of clay. Not sure why you picked what you picked but something to test with. From here, dial in or check the fit and adjust silica to desired matte and feel as well as tin for color. Mattes can be a challenge to get a fit, so moving the R2O towards 0.2 while leaving the alumina relatively high to keep your 5 ‘ish si:al ratio is a technique to reduce the COE if this crazes on your clay
  21. Maybe one of these? https://www.google.com/search?source=univ&tbm=isch&q=Vintage+Toy+Maker+Santa+%26+Mrs+Claus&client=safari&fir=6lO7BJ2W3hcT1M%2CJKY-W-7c9joDGM%2C_%3BiRXeVLVX5S0GOM%2C_W75EhQL5Tj0TM%2C_%3BHPkkgLhakUMQYM%2C_W75EhQL5Tj0TM%2C_%3B4nQUBg4ptf1MpM%2CQh-q9jNGiKBSDM%2C_%3Bb44HOAuLpwrFNM%2CSWU9gas_InH8qM%2C_%3BllLRIapUILnMnM%2CoTEUtLAQjFGIxM%2C_%3B5JyZBT_By_CIqM%2C_W75EhQL5Tj0TM%2C_%3B-McqVgDuMd7ioM%2CRhhuhHeqyHmWTM%2C_%3BOKXHwlk12nJ9IM%2ChQMuBuhOPel_oM%2C_%3B7IzUxg241GjgmM%2C_W75EhQL5Tj0TM%2C_&usg=AI4_-kRODZIaiq5r442k_D6A2LxP1-WA-w&sa=X&ved=2ahUKEwjk_sDwoKrzAhVVK80KHcUwB3AQjJkEegQICxAC&biw=1121&bih=728&dpr=2
  22. What is the basis for this recipe? It appears like not enough boron, assuming cone 6, and lots and lots of clay considering China clay and calcined kaolin.. Is this a recipe you have proven is good for you? It has a fairly non standard flux ratio, that aside it should fire matte by the looks of its si:al ratio and your picture seems to indicate it does that. Normally I would suggest to try: raise the boron to 0.15 for cone six and add silica until it is the desired sheen or feel. I am apprehensive about it because of the flux ratio and with double the clay in it I can’t help get the feeling one of these ingredients should be a feldspar and there is a transcription error in this recipe. Glay recipe UMF below
  23. Not sure I follow. This kiln contains six elements, center section are series connected to form a pair or four elements total, top, bottom and two center.. Single phase to three phase conversion by transformer is very difficult . Again, lots of speculation though. Best thing I think, is to know everything about the kiln, operating voltage, intended wattage, resistance and start designing from there.
  24. Seems like a good idea. Not sure what to think about the lead and arsenic potential though. Oh well, enjoy, stay safe.
  25. I am not aware of anything simple. My thinking is we really need to look at the present service, 240v single phase and decide is it easier to convert the kiln or do we really want to change 240v single phase to 208v three phase in a pure resistance environment. My strong hunch is convert it to 240v single phase operation
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