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kristinanoel

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About kristinanoel

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    juniper-clay.com

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    Tacoma, WA

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  1. "you can go as fast as you like as long as your claybody doesn’t suffer any issues from incomplete burnout. " ha! Makes sense - also makes sense that the ranges to watch are between 300 - 600F for organics, ~1200F - 1750F for sulfides and inorganic carbons. I find it more helpful to think about what each segment is trying to do, less helpful to identify the "magic number", as you so cleverly put it! Thank you for your story. Sounds like you made some really good memories and a lot of good friends.
  2. Thanks Bill! I'll always listen to an opinion. That's exactly why I posted. And Just to be clear - I'm not doubting the reliability or efficacy of the Bartlett program, I ask questions so that I can develop a better understanding of the reasons behind the choices. For example... that standard limit of 300F per hour - I reckon that's to smooth the transition for atmospheric or chemically bound water?
  3. Thanks, Min - that was a great article! Because I do work with iron rich clays, I'm adding additional time for that organic carbon burn off between 300 - 600, and keeping the slower ramp for the inorganic. On the 1000F - 1100F quartz inversion slowdown - such a lot of conflicting information here. Most of the what I've read has included this slowdown phase in the bisque but not in the glaze, as in the example that Bill posted. My understanding was that the focus for the glaze firing is to achieve maturity for both clay and glaze in the ~1950F - 2190F range, hence the fast ramp to high bisque temperature. From what I have learned, it seems that the majority of problems occur on the way down from 1100F to 1000F, as there is less available room for movement. Has that been your experience? I've not experimented with slowing the cooldown, but may incorporate that into future firings.
  4. Thanks for replying! More questions, if you're up for them? When I compare the two schedules, there are a couple of differences in the bisque thatI'd like to understand. The cone 5/6 schedules aren't materially different (slightly lower target for segment 1, faster for segment 2, and higher temp to end). For the bisque: In the initial temperature rise to 1000°, the auto schedule starts at a slow rate of 80°/hr to 250°, then includes a med ramp of 200°/hr to 1000. What's happening with the clay here? is there some reason this stage needs 6 hours rather than 3? Post quartz inversion slowdown, the rate of 180°/hr is higher than I would have expected to burn out sulfides and organic materials. Is that faster speed sufficient for darker clay bodies? What's going on in that final slower 80°/hr segment? Just for temperature regulation, or something else? Segment 1 Segment 1 What's going on here? slow warm to elements or for drying clay? Goal bring ware to even, pre-qartz inversion temperature Goal target temp 1000° target temp 250 temp change ~935° temp change 185 Rate 325°/hr Rate 80 Hold 10 minute even core / surface temp Hold Approx. time 3 hours Approx. time 2.25 Segment 2 slower rate - why? is something going on with the clay? Goal bring ware to pre quartz inversion target temp 1000 temp change 750 Rate 200 Hold Approx. time 3.75 Segment 2 Segment 3 no difference Goal slow ramp for Quartz Inversion Goal slow ramp for Quartz Inversion target temp 1100° target temp 1100° temp change 100° temp change 100° Rate 100°/hr Rate 100°/hr Hold 0 Hold 0 Approx. time 1 hr Approx. time 1 hr Segment 3 Segment 4 faster ramp rate - why? Goal allow sufficient time for organic materials to burn out of clay Goal target temp 1925° target temp 1695° temp change 815° temp change 815° Rate 125°/h Rate 180°/h Hold 15 minute soak to even surface/ core temperature Hold Approx. time 7 hrs Approx. time 3.3 hrs Total time ~ 11 hrs Segment 5 why so slow? just so that no hold is needed, or some other reason? Goal bring ware to temp evenly between surface/core target temp 1945° temp change 250° Rate 80°/h Hold Approx. time 3.1 hrs Total time ~ 13 hrs Thanks!
  5. Hi everyone - I've spent the last few hours combing through the forum to learn more about the factors to consider in setting up a firing schedule, I've come up with a plan and would love to hear feedback, and/or anywhere I've gotten the wrong end of the stick. I'm bisque firing to 04, glaze firing to 5 in an electric kiln with a bartlett controller. Any advice is welcome! 04 Firing Schedule Segment 1 Goal bring ware to even, pre-qartz inversion temperature target temp 1000° temp change ~935° Rate 325°/hr Hold 10 minute even core / surface temp Approx. time 3 hours Segment 2 Goal slow ramp for quartz inversion target temp 1100° temp change 100° Rate 100°/hr Hold 0 Approx. time 1 hr Segment 3 Goal allow sufficient time for organic materials to burn out of clay target temp 1925° temp change 815° Rate 125°/h Hold 15 minute soak to even surface/ core temperature Approx. time 7 hrs Total time ~ 11 hrs Questions: Is the first segment too fast? Assuming ware has been candled and there is no atmospheric water, what am I risking? Can I speed up segment 3? Seems inordinately long, but I am trying to 1) give enough time for organic materials to burn out, especially as I use dark clays, and 2) accommodate the target rate range for the last ~150° so that I can get accurate readings of the cones. Anything glaring I didn't know to ask? Cone 5 Firing Schedule Segment 1 Goal dry any atmospheric water from glazing target temp 300 temp change 235° Rate 150°/hr Hold 0 Approx. time 1.5 hours Segment 2 Goal bring ware to even, high bisque temp target temp 1925° temp change 1625° Rate 325°/hr Hold 20 minutes to even core / surface temp Approx. time 5 hours Segment 3 Goal slow ramp for sodium/potassium offgassing target temp 2150° - (mid cone 5 range of 2118° - 2205°) temp change 225° Rate 125°/hr Hold 10 minutes to even core / surface temp Approx. time 2 hrs Total Time 9.5 hours Questions: Do I need a Quartz Inversion segment in glaze firing? In some of the sample schedules I've seen them, but have also read that this is more of an issue in the first firing? Any other reason to break up or slow down that middle segment? It seemed like the goal was to pull the ware up to bisque temp asap, and then slow down for clay and glaze maturity, but is there something I've missed? Anything glaring I didn't know to ask? All comments welcome! Kristina
  6. I have had the same issue as Min, and as I sometimes leave the exterior of pieces unglazed, I find that it IS a problem for me. I fire to cone 5. After it's fully dry, I wipe away anything visible (a couple of times, letting it dry in between) which sometimes works, but not always. When it doesn't it will fire with a dingy grey or yellow effect - kind of fine if there are no exterior decorations, but if I've used any kind of tape mask to add an iron stain or wash, I've got problems - a sharp line where the soluble materials were not able to emerge due to the tape. I've tried a 50/50 vinegar solution, hasn't been 100% effective, so I'm considering getting a masonry efflorescence cleaner to do a more effective job - has anyone tried that? This one and this one both use Urea Monohydrochloride instead of Muriatic acid.
  7. Hi Rebecca - I also spotted that post and am super interested in hearing about your results. Please post if/when you start experimenting. And if anyone else has tried something like this (especially if you have tips about what really, really won't work) I would love to know more. Seems like you could wedge some into clay and fire, especially if no glaze was required, but I'm not sure about what the best case/worst case scenarios even are. Thanks for bringing up this topic!
  8. I know it's a drive from Ellensburg, but Clay Art Center in Tacoma makes some great stoneware bodies. Here's a link to some of the white/off white options (this is page 3 of 3, go back to see other CAC clays) http://www.clayartcenter.net/~clayar5/content/index.php?main_page=index&cPath=35_92_97&sort=20a&page=3
  9. Hi Terah - what lucky kids, to have a ceramics studio in elementary school! That long soak may be the candling phase - keeping the kiln under 200F to make sure all of the ware is actually dry. This is probably especially useful if the kids are making thick or heavy sculptures that might take weeks to dry on their own. So the overnight candling, followed by full day of drying out before firing probably helps in making sure the work doesn't crack or explode during the actual firing.
  10. Well there you go. Leave out the zinc oxide and it won't be perfect! (Might not even be perfect if you had the zinc.) Win-win.
  11. Also - what exactly is the assignment? To find and test a cone 10 glaze recipe? Why not just find a different recipe that only calls for stuff you have? https://glazy.org/
  12. You could just leave it out and see what happens. You've got talc and whiting, which are also fluxes, and not that much zinc oxide anyway. Think about what each of the elements is meant to do, make glass, stick to the pot, or help the glaze melt. As my professor was fond of saying: "Might work, might not. Try it and see." Glassmakers / Glaze Cores custer feldspar 99 silica 48 Binders EPK 45 Fluxes talc 63 Whitening 36 zinc oxide 9 Colorants +22.5 titanium oxide 6 copper oxide black 6 copper oxide red
  13. Love it! Beautiful design. Signed up for your notification list. Also - it would be great to see a video of it in use - is it messy? Since you're pushing laterally rather than down, is it tricky to use? Would also love to see it pouring - spouts are so hard to craft with clean pour. I've been trying to make a little milk pourer for about a year now and every single one just kind of dribbles.
  14. I have tried the silicone rings in the past, I found them to be a lot of trouble to get on/off, and they didn't really work for me, as they can be compressed. I just ordered these rollers - theoretically they should work great but...theories have certainly failed me in the past! When they arrive I'll report back and tell you how they work - I'm planning on only using them for small slabs I want to make on the worktable, I have a roller for larger slabs, but wanted something more convenient for cutting out little things.
  15. I had the same problem - I the sliders, not the arms, and I've started using cotton pads in between the mug and the slider to protect the ware. Works great, and size/thickness is uniform so I don't have to worry about things getting out of alignment.
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