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C.Banks

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Everything posted by C.Banks

  1. The studio was relocated and the electric kiln never got hooked up again. Combustion sure has a lot to say about just how successful you think you will be
  2. When we were firing in oxidation I was lucky enough to have 3 glazes that I was satisfied with. They fit, played very nicely, behaved on the pot as well as in the bucket. They were complete for the most part. The public liked them and could match pieces from year to year. They took a few years to develop but they were complete in my eyes. This was a few years ago so a decades worth of perspective might offer some insight but I'll leave them for some other year.
  3. I'm working with a clay that has a tendency to flop with little warning. From what little I know this can be a problem with plastic clay bodies holding more water than more forgiving, less plastic bodies. So with this in mind I'm looking at making adjustments but I'm getting conflicting information on what some accepted water content values are. Plainsman P700 has a % water of 23.5 - 24.5 Plainsman describes P700 as "our most vitreous cone 10 white body, it is the closest thing we have to a true translucent porcelain body. It is a mix of 50% Grolleg kaolin with feldspar and silica. We also add micro-fine bentonite to improve its plasticity." In the Febreuary Ceramics Monthly (thanks Tom) the water contents are significantly higher than the figures from Plainsman. I'm wondering are clays so different in the Unites States? I'm curious because the clay I'm working with holds aproximately 26% and is mixed up as a high fire, buff, stoneware. It works well for the most part. Fires to an 11 with no issues and kitchen tested absorption showed it was near zero at cone 10. But it doesn't stand up as well as the commercial Plainsman clays and I want to know why. thoughts much appreciated 20 epk 20 OM-4 ball clay 20 silica 20 custer potash feldspar 12 hawthorn Bond Clay 8 pv clay Percentage Analysis by weight 71.13 % SiO2 23.24 % Al2O3 3.06 % K2O 0.73 % Na2O 0.28 % CaO 0.32 % MgO 0.59 % Fe2O3 0.05 % P2O5 0.59 % TiO2
  4. C.Banks

    clay plasticity/water content

    After a few tests this clay still requires about the same water. I'm hoping when the studio comes out of winter storage the performance on the wheel might improve. I'm looking at dropping the epk alltogether. I knew it was a bit out of place next to a fireclay.
  5. I hope people continue to realise what a plague plastics are to the world. I suspect folks who care to curb plastic use will appreciate a nice crock or three.
  6. C.Banks

    Alabama Rain

    @HulkThe 70's and 80's were a good time to establish a studio. Establishing a pottery today is a bit more...cumbersome. I've always liked Bill van Gilder but never took the time to appreciate the man better so thanks for the video. The influence of Michael Cardew explains more why I like his style. I wonder if he spent any time with Ray Finch in Winchcombe. @Babs10% rutile does seem like a lot. I have a bit of a love-hate relationship wiht rutile/titanium. As you probably are already aware differences in cooling cycles will drastically affect results with rutile/titanium. The most I've seen used in a shop glaze is 6%. The most I've used is closer to 4 in oxidation. That 2% whiting sticks out as almost irrelevant as well. The glaze looks well enough supplied with calcium without it. This is for an electric kiln? I ask because from what I understand zinc is wasted in reduction. *I thought i better try to find the information on zinc again. This clayarts discussion gets into into it a bit. Suffice to "...say that zinc-containing glazes may be quite variable and unpredictable in reduction depending on how carefully you duplicate conditions firing to firing and how uniform the interior of your kiln is." John Hesselberth
  7. This requires some brutal honesty and a merciless hammer. A person once told me there was enough crap pottery in the world she didn't want to add to it. She was a forthright person and I liked her. I sometimes garage sale or cruise thrift stores with potters who find their own work. They smile and handover a few dollars and if necessary say something like "ya' - it's ok" all the while thinking how quickly the hammer will fall. I like these people too. I hope to find something of my own one day and it would be nice to feel as though it deserved a good home away from hammers and rocks and piles of shards.
  8. I borrowed a vl whisper after coming from a motorised kickwheel and had this same experience. There was even an old clayarts discussion about a similiar story. I couldn't find the original but this is a discussion of the discussion. What I found was my wheel speed on centering with this shimpo was too fast - or at least slowing the wheel down while centering helped. I was taught to center as fast as the wheel would go. The kickwheel showed me this speed was not necessary and the slower speed agrees with a vl - at least in my experience. I'm unsure if the sound the motor makes has anything to do with it but I definitely accused it as well. I still don't throw as well on a vl whisper as I do on a nice fly-wheel but I get by well enough.
  9. At this risk of drawing forum ire I'm inclined to gently suggest that mocking people is insincere and counter productive.
  10. C.Banks

    Rice ash glaze recipe adjustment

    Uncertainty in results drives me a bit around the bend at times. If you have rice straw ash that you are certain of you can help to eliminate some uncertainty by melting a small amount of known material alongside what may be misidentified material. Melt tests are useful for comparing all sorts of stuff.
  11. C.Banks

    Rice ash glaze recipe adjustment

    I was curious and found this clayart post. I would suspect rice hull rather than rice straw ash as well - or a mistake in the mixing. A blend with gerstley borate is a good thought. I'd try 5, 10, 15, 20. 5% might not be enough and 20 sounds like a lot but smaller increments will help narrow the number. This is a good place for ceramic adventures. Goodness knows we've all had our share of ??? moments.
  12. Carlton Ball explained in an old publication how soluble salts can be used in a solution and allowed to soak into craze lines. The pot is refired and the craze lines heal but the salts have migrated into the clay body and result in a feather like effect. If I remember right craze lines are forced by using a midrange glaze on a highfire body and fired once to cone 6 or so. The pot is soaked for a short time, wiped clean of the salt solution and refired to cone 10 healing the craze lines but leaving the trails behind in the clay. They are tiny, tiny colloidal molecules from what I understand and must be used carefully. "Decorating Pottery with Clay, Slip and Glaze" by F. Carlton Ball a Ceramics Monthly publication from 1967 He mentions it again in a bit more detail in "syllabus for advanced ceramics" a Keramos publication from 1972. I appreciate this isn't what you were after but thought I could add it here for others to find. @Marcia Selsor recently posted about using salts too. I'll bet she knows a thing or two.
  13. C.Banks

    Article out today

    "This year I had five kilns but only five good works (not good, ordinary) and we wish to break up all the others (50) but if we break up all of them we must ask 100 yen each for the five works. Then who will buy? Can they buy? Well if they cannot buy how shall we live?" Sometimes I'm glad I have a second life.
  14. While looking into shrinkage rates and cracks and plasticity I found a picture I immediately recognised. This picture exactly matches something I've encountered. I thought maybe it was the result of some 60 mesh silica sand I was trying but now I suspect not. As someone looking for any clue along the way this small tidbit helps a bit. Thanks Tony and anyone else at Digitalfire.
  15. Speaking of metal and 'stems' this was an interesting discussion ... almost 7 years ago ...
  16. C.Banks

    clay plasticity/water content

    My suggestion of a 'solution' was my way of trying to understand a dense (fine?) kaolin 'diluting' a molar % I'm sure more of this will will sink in over time. I have to re-read stuff to try to untangle and think through the more complicated ideas. I'm looking forward trying these adjustments when my materials arrive. I may have been able to stumble around on my own but this save me a bunch of trial and error and error.
  17. C.Banks

    clay plasticity/water content

    That's the plan as long the three I'm looking don't have any obvious issues like creeping LOI values.
  18. C.Banks

    clay plasticity/water content

    I was trying to understand this in terms of particle size and surface are but if large particle fireclay has less surface area this should, in my mind, mean less KNaO is required to encapsulate. More dense, smaller particles have more surface area so would require more KNaO to encapsulate. "ball clay is denser than kaolin. Being denser, it dilutes the concentration (molar%) " Dilute to indicate a weaker solution so less available ... KNaO?
  19. C.Banks

    clay plasticity/water content

    I'm unsure how particle size increases KNaO amounts. Unless the KNaO amounts must be increased out of necessity.
  20. C.Banks

    clay plasticity/water content

    The easy answer is the fireclay but I have a suspicion this is not what you are getting at.
  21. C.Banks

    clay plasticity/water content

    clay clay Code Number: NPC2 Code Number: NPC3 ========================================= ========================================= EP Kaolin................... 25.00 EP Kaolin................... 25.00 A2 Ball Clay................ 15.00 A2 Ball Clay................ 15.00 Plainsman Fire Clay......... 20.00 Plainsman Fire Clay......... 25.00 Custer Feldspar............. 20.00 Custer Feldspar............. 20.00 Silica...................... 20.00 Silica...................... 15.00 ========= ========= 100.00 100.00 Oxide Formula Analysis Molar% Oxide Formula Analysis Molar% CaO 0.00 0.20%w 0.24%m CaO 0.00 0.21%w 0.25%m MgO 0.00 0.14%w 0.24%m MgO 0.00 0.15%w 0.26%m K2O 0.03 2.81%w 2.01%m K2O 0.03 2.94%w 2.12%m Na2O 0.01 0.88%w 0.96%m Na2O 0.01 0.94%w 1.04%m P2O5 0.00 0.06%w 0.03%m P2O5 0.00 0.06%w 0.03%m TiO2 0.00 0.37%w 0.31%m TiO2 0.00 0.41%w 0.35%m Al2O3 0.21 22.65%w 15.00%m Al2O3 0.22 24.22%w 16.17%m SiO2 1.11 71.91%w 80.80%m SiO2 1.08 69.98%w 79.32%m Fe2O3 0.01 0.98%w 0.41%m Fe2O3 0.01 1.09%w 0.46%m Cost: 0.08 Cost: 0.08 Calculated LOI: 7.09 Calculated LOI: 7.52 Imposed LOI: Imposed LOI: Si:Al: 5.39 Si:Al: 4.90 SiB:Al: 5.39 SiB:Al: 4.90 Thermal Expansion: 232.41 Thermal Expansion: 242.83 Formula Weight: 92.91 Formula Weight: 92.48 Recipe Date: 2019-01-27 Recipe Date: Today's Date: 28/01/2019 Today's Date: 28/01/2019 Recipe name or ID: 185 Recipe name or ID: 186 Location: Location: Typecodes: Typecodes: Batch Size: 0 Batch Size: 0 STANDARD.XML STANDARD.XML
  22. C.Banks

    clay plasticity/water content

    The CnC version looks like it has a nice Si:Al right out of the box. The molar KNaO is only 2.66% but it's not far off. Code Number: CNC Code Number: new Plainsman clay ========================================= ========================================= EP Kaolin................... 20.00 EP Kaolin................... 25.00 Silica...................... 20.00 Silica...................... 15.00 Custer Feldspar............. 20.00 Custer Feldspar............. 20.00 Hawthorne Bond.............. 20.00 A2 Ball Clay................ 20.00 C & C Ball Clay............. 20.00 Plainsman Fire Clay......... 20.00 ========= ========= 100.00 100.00 Oxide Formula Analysis Molar% Oxide Formula Analysis Molar% CaO 0.00 0.19%w 0.23%m CaO 0.00 0.21%w 0.26%m MgO 0.00 0.21%w 0.36%m MgO 0.00 0.16%w 0.28%m K2O 0.03 2.59%w 1.87%m K2O 0.03 2.86%w 2.07%m Na2O 0.01 0.72%w 0.79%m Na2O 0.01 0.89%w 0.98%m P2O5 0.00 0.05%w 0.02%m P2O5 0.00 0.06%w 0.03%m TiO2 0.01 0.84%w 0.71%m TiO2 0.00 0.41%w 0.35%m Al2O3 0.23 24.85%w 16.59%m Al2O3 0.22 23.82%w 15.87%m SiO2 1.08 69.84%w 79.12%m SiO2 1.08 70.49%w 79.71%m Fe2O3 0.00 0.70%w 0.30%m Fe2O3 0.01 1.08%w 0.46%m Cost: 0.08 Cost: 0.08 Calculated LOI: 6.70 Calculated LOI: 7.62 Imposed LOI: Imposed LOI: Si:Al: 4.77 Si:Al: 5.02 SiB:Al: 4.77 SiB:Al: 5.02 Thermal Expansion: 221.22 Thermal Expansion: 237.63 Formula Weight: 93.30 Formula Weight: 92.38 Recipe Date: 2019-01-27 Recipe Date: 2019-01-26 Today's Date: 27/01/2019 Today's Date: 27/01/2019 Recipe name or ID: 184 Recipe name or ID: 180 Location: Location: Typecodes: Typecodes: Batch Size: 0 Batch Size: 0 STANDARD.XML STANDARD.XML
  23. C.Banks

    plastic clay and drying performance

    Hindsight is one of my greatest assests too! Social media would be a far better place if this quality was shared more widely.
  24. C.Banks

    clay plasticity/water content

    These numbers look very specific. Do they come from a chart or formula? Plainsman has a clay I like and because they are generous with their data, unlike some others I won't mention, I can use them as a bit of a guideline. H555 CaO 0.6 K2O 2.0 MgO 0.5 Na2O 0.3 TiO2 0.7 Al2O3 20.9 P2O5 0.0 SiO2 65.5 Fe2O3 1.1 MnO 0.0 LOI 8.3% This is, I'm presuming, a percent by weight but I can still get a sense of where the Si:Al falls in relation to KNaO. I'm sure there is a way to input the percents into Hyperglaze and convert them but I'm tired of trying and failing. and I just remembered about a garage sale I'm missing
  25. C.Banks

    clay plasticity/water content

    Understanding Clay Body Formulation "This three-part series will discuss the many business and technical issues that should be considered when creating/evaluating a clay body formulation. " (Jeff Zamek, https://www.ceramicindustry.com/articles/90298-ppp-evaluating-clays) Another helpful online resource for anyone else mucking about at the bottom of a hole.
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