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F Crow

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  1. That's very interesting to hear as so often soaks are mentioned in firing schedules I've come across. No harm in trying it though, so will give a go at firing to 1200oC without the soak in a firing soon too.
  2. Hi Bill, I added the soak with the thought that it would insure that the entire chamber had reached 1200oC. Feared that without it some pieces (perhaps towards the bottom of the kiln) may be slightly underfired as the temperature range of the clay is 1200oC-1290oC. I do intend on firing without a soak as you recommended when firing to 1220oC though as this shouldn't be an issue. Hope my logic isn't too flawed in this thought...
  3. UPDATE Tried a firing of; -150oC/h to 1000oC -60oC/h to 1200oC -15min soak Had a good result with the dark glaze. The surface still isn't completely smooth, but a massive improvement! Unfortunately there was no difference with the light blue glaze though. I actually bought a new batch and tested both the new and existing glaze in case the one I had was contaminated, but both turned out the same... Riddled with pits! Will try another firing soon and go to 1220oC to see what happens there. If that doesn't help then the manufactures have asked to send them some bisqueware to test the glaze themselves. Have also emailed Nabertherm about updating the controller so awaiting their response.
  4. I am not sure either to be honest. Would guess that maybe it is the programming of the controllers that differ and allow for more programmes and more segments... But again, I know almost nothing about electronics. There is a USB port in the controller that allows programmes to be created externally on computer and imported, so maybe I could upgrade the controller from a B400 to C440 via that port... I will actually email Nabertherm and find out if that is a possibility. Nothing ventured nothing gained! Thanks again for the help.
  5. Yeah if ever changing kiln in the future I will be more diligent and research into the controller like you, not just the size and amperage as I did with this one... Not sure if ny controller can actually be changed upon further examination. However I know very little about electrics. Thinking that if this is the case, it may be why the upgraded controller cannot be bought separately though.
  6. Apologies for the slow response, busy few days. Know very little about electrics, but having looked at my controller now perhaps it actually cannot be changed and that is why they won't sell the upgrade unless with a kiln as it must be made together...
  7. I have a Nabertherm top 80 kiln with a Nabertherm B400 controller. Wish I could upgrade to the C440 controller as this allows up to 10 saved programmes with up to 20 segments in each, but it doesn't seem that it can be purchased without buying a kiln at the same time...
  8. Thank you so much for the informative response. Definitely seems to be more variety in approaches to firings out there than inconsistencies. Makes it a hard field to navigate and figure out! The manufacturers actually ran a test of their own with one of the troublesome glazes using a firing schedule of; -500oC/h to 1030oC -75oC/h to 1200oC -15min soak And they claim to have had no issue... However they didn't recommend going as fast as they did in the initial segment. So I will definitely give a go with a faster first segment leading into a slower rate at the end of 60oC/h for the last 2 hours. Putting a bisque on today so will be a few days before I get to try it out.
  9. Thanks again for the advice, it is very appreciated! Wish I had learned these things when studying ceramics, but from reading around online it seems tutors skipping over theory about firings etc isn't uncommon practice. Try to learn as much as possible reading various sources but there are so many variables in the world of ceramics it's hard to weed out what is relevent/reliable and what is not. All my work is hand built, either slabs or press molds, and never thicker than 6mm (or approximately 1/4inch) and I leave ware at least a day after glazing to dry out before packing into the kiln, so hopefully a faster first segment shouldn't cause any harm.
  10. It is a similar thought I was having when contemplating dipping the pieces in water. Among other things I make bowls using a press mold and they are very fine (maybe 3mm thick when fired), so even after dipping them in the glaze they can sometimes take a while to dry depending on the glaze consistency. I too have it in mind as a firing issue which is why I started this thread with a kiln question. Have been trying to come up with potential causes for weeks now and tried so many things (even bought a dehumidifier for the studio!) and the only varient that seems to cause any difference is the firing schedule.
  11. Sorry if I came across as dismissive, I was just trying to understand the reasoning behind your advice. There is so much to learn in ceramics and I certainly admit to having big gaps in my knowledge. It's just not a suggestion I've never seen elsewhere.
  12. Thanks for the advice, definitely seems that what is available to me in Ireland has more limitations than in the US from reading online. Would picking a mid speed segment going up initially be a good option maybe? Something like; - 100oC/h to 1100oC - 60oC/h to 1200oC - drop to 1145oC -20min hold
  13. Sorry I'm not sure I understand what the benefit of dipping the bisque in water would be? I have seen that wiping with a damp sponge will remove potential dust and help the glaze adhere to the bisque as water attracts water. Not sure what the advantage therefore would be in dipping it entirely in water? Could this not just waterlogged and saturate the ware making it difficult for it to receive an adequate glaze layer?
  14. Thanks for the suggestion however this is where my controller only allowing 4 segments becomes an issue. When inputting a schedule like this it would be (at least) 5 segments. 1-60oC/h to 120oC 2-180oC/h to 1100oC 3-60oC/h to 1200oC 4-9999oC/h to 1145oC 5-20min hold This is why I've had problem coming up with a schedule as it seems I'd have to either go fast at first, to slow at top, drop, then soak, or else go slow at first, faster than desired at top, drop, then soak. Obviously neither option is great....
  15. Thanks again for your reply. The glaze is meant to be glossy alright. I have had success with it in the past, but thinking of it now that was on smaller pieces with texture so that may have hidden the defect? None of my glazes move beyond the glaze line (with the exception of one crystalline glaze but I think that is to be somewhat expected) as I use them slightly thinner than recommended. Unfortunately I don't know the composition of the glaze as it is commercially bought. This isn't the only glaze I've been having this problem with however. I'll attach a photo here of another piece with a different glaze showing the same issue. Yes from what I've read a drop and soak schedule does sound like a potential solution! I found a cone 6 schedule on digitalfire but it contained too many segments for my controller so I had to edit it. It did help somewhat but ultimately didn't eradicate the issue. Would you know of a drop and soak schedule that would be worth a try that contains no more than 4 segments, around cone 5 1/2 or 6 temp?
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