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PeterH

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  1. Like
    PeterH reacted to Jeff Longtin in Difference between Dry Clay and Dry Casting Slip?   
    Most casting bodies are 50% clay and 50% non clay. Most throwing bodies have a greater percentage of clay in them.  Throwing bodies are designed to be plastic. This increases their shrinkage. (Both before and after firing.) You want to have shrinkage, in a casting body, but not too much.  (Enough so the casting pulls away from the plaster mold but not so much that the casting cracks while setting up in the mold.) Some throwing bodies can be turned into casting slips but most are too plastic. 
    Another factor that determines how well a clay body will cast is the actual size of the clay particles. (Some porcelains are made up of small particles and some are made of larger particles.) A well designed casting body will have a balance of both large, and small, clay particles.  
  2. Like
    PeterH reacted to Bill Kielb in Cone 6 to cone 10 glaze   
    Maybe .......... in reduction you are looking for a way to set up favorable conditions for something  to gain electrons, hence reduction reaction. If you are firing cone 10 with fuel then carbon monoxide is your friend and only a handful of oxides are affected anyway so learning how to achieve and hold a level of reduction is the challenge. If you are firing cone 10 in an electric kiln, it will be very hard on the kiln elements decreasing their life to 25% or less than cone 6 so I suspect you will not do that for long. SIC can potentially get you local reduction, but defining exactly what you are trying to do to what materials will be important to figuring out likely successful tests. It’s not necessarily a cone 10 thing actually.
    So if I understand correctly you are seeking reduction effects on certain oxides and your plan is SIC regardless of temperature. Again, not bad to search Glazy for similar results at the cone you want to fire. If you are using SIC to make a volcano glaze, then search for that as well. Each will require learning some chemistry of what you intend to happen which will be a good thing. Not necessarily a cone 10 thing though so converting cone 6 to cone 10 maybe not as relevant as you originally thought.
    maybe Post exactly what you are trying to do here (especially with respect to reduction, including color, oxides, etc...) and see if someone has a recipe that is tried and true. Often learning from the research of others saves a bunch of time learning.
  3. Like
    PeterH got a reaction from Hulk in Fuddling Cups   
    Loosely related modern idea.

    When ordering drinks at the bar, guests could ask for theirs to served in one of the sculpture's individual compartments. When all three cups were filled, (ideally with drinks ordered by three strangers) the newly-formed trio could cluster together, introduce themselves and forge new connections.
    Drinking from one compartment without spilling from the others is a challenge that requires communication, coordination and teamwork, akin to a corporate team building activity, albeit a boozy one.
    http://www.jonsasaki.com/index.php/work/cluster/
  4. Like
    PeterH got a reaction from Beded in Curing with laser heat treatment   
    @Magnolia Mud Research  That's not how I interpreted the OP's query, and I would be interesting in his response.
    You are of course right that lasers enable a variety of 3D printing techniques, not least because of their ability to be focused precisely. Ceramic 3D printing seems to be no exception, and 3D printing of ceramics: A review tinyurl.com/45cvhhrk includes details of laser sintering and laser melting applied to the production of ceramic parts.
  5. Like
    PeterH got a reaction from Magnolia Mud Research in Curing with laser heat treatment   
    @Magnolia Mud Research  That's not how I interpreted the OP's query, and I would be interesting in his response.
    You are of course right that lasers enable a variety of 3D printing techniques, not least because of their ability to be focused precisely. Ceramic 3D printing seems to be no exception, and 3D printing of ceramics: A review tinyurl.com/45cvhhrk includes details of laser sintering and laser melting applied to the production of ceramic parts.
  6. Like
    PeterH reacted to Magnolia Mud Research in Curing with laser heat treatment   
    Several years ago Arnold Howard posted about laser cutting being used to "cut" the bricks used in  paragon kilns.  
    Laser heating can be used along with 3D construction of many materials. Powdered materials placed properly and zapped with energy to cause the particles to fuse together.  I have "fired" small greenware ceramic items with a propane hand torch, start to finish in about 2 minutes.  
    Get out of the standard "wheel and kiln" box and THINK.    Try it; feed the raw materials to the laser in the right size bites at the right time and the concept should work. 
    a few years ago, 3d ceramics was unknown.  Now it is proven to work for both art and certain industrial production products. 
    LT
     
  7. Like
    PeterH reacted to Magnolia Mud Research in Hotter Inside a Cup?   
    Mark  What do you mean by "the lack of atmosphere"?  
    There will always be an "atmosphere" in an open area even if the atmosphere is just a perfect vacuum.  The composition of the atmosphere inside a cylinder is likely to be somewhat different than the more open and connected volumes.   movement of atmosphere in a combustion kiln is different in many ways from the atmosphere in an electric kiln.  Composition for one; constant movement another.   
    My experience with "pinholes" at cone 3 oxy and cone 10 reduction have been application issues not firing conditions.  glazes bubbles and blisters are glaze composition and local melt temperature problems.    (our differences may be in the definition of "pinhole").  
    My answer to Rick's question:   The temperature on the internal surface of a cylinder will always be lower than the cylinder outside surface during the firing period.  During the "hold" time the temperatures will tend to come closer.  During cooling step the internal surface will tend to be hotter than the outer surface since the heat stored in the ware must migrate to the kiln insulation and then to the outside environment.  The differences between the outer and inter surfaces temperatures depend also on the local thickness of the cylinder and the properties of the materials of both the clay body and the glaze(s) used.  
    LT
     
  8. Like
    PeterH got a reaction from Benzine in Hotter Inside a Cup?   
    Interesting question. Could it get more heat-work by cooling slower? Much of the radiation from the inside a cup will presumably hit somewhere else inside the cup, while radiation from the outside the cup will mainly go away from the cup.
  9. Like
    PeterH reacted to Bill Kielb in Hotter Inside a Cup?   
    All good points actually. Is the material conduction slow enough to influence the cool down so it is outside in at a meaningful rate? I think time to throw some open cylinders set on a cookie and fit cones inside.
  10. Like
    PeterH got a reaction from Bill Kielb in Hotter Inside a Cup?   
    Interesting question. Could it get more heat-work by cooling slower? Much of the radiation from the inside a cup will presumably hit somewhere else inside the cup, while radiation from the outside the cup will mainly go away from the cup.
  11. Like
    PeterH got a reaction from liambesaw in Hotter Inside a Cup?   
    Interesting question. Could it get more heat-work by cooling slower? Much of the radiation from the inside a cup will presumably hit somewhere else inside the cup, while radiation from the outside the cup will mainly go away from the cup.
  12. Like
    PeterH reacted to neilestrick in Curing with laser heat treatment   
    A laser would be far too focused. Clay needs to heat fairly evenly to avoid cracking, warping, exploding, etc. 
  13. Like
    PeterH got a reaction from Babs in White spots coming through blue overglaze   
    What are the small white dots ringed in this picture?

  14. Like
  15. Like
    PeterH reacted to GEP in Question about alternative finishes for ceramics & acceptance by ceramic artists   
    Several people have offered the answer “no the painted surfaces are not ceramics” but you won’t take that for answer. And you defend your position by arguing an “art” defense but not providing a “ceramics” defense.  That’s why it doesn’t seem like you understand that these are two different questions. 
  16. Like
    PeterH reacted to neilestrick in Question about alternative finishes for ceramics & acceptance by ceramic artists   
    You are underestimating what glazes can do, just as others are underestimating what alternative finishes can do. Both opinions are shortsighted.
    I think a lot of people who work in ceramics see cold finishes as a shortcut, because they can generally be removed or covered over if they fail, and don't have to deal with the complications of heat and other technical issues inherent with ceramics. Working with clay is only half the process in ceramics. It's kind of like making your own pasta but using canned sauce. As someone that is dedicated to ceramics, I understand that opinion, and agree with it to a degree. I also agree that there is nothing wrong with cold finishes, but I wouldn't consider your work to be ceramic, as to me that implies that the entire thing is ceramic. If I were shopping for ceramic tiles or plates, I would not expect them to have a finish that was anything other than a fired-on ceramic finish. I would call your work mixed media, and would describe it as stoneware (or whatever type of clay you're using) and paint, wax, etc. It may seem nitpicky, but it removes any ambiguity.
    In reference to the piece you posted a picture of with the cubes and the ball, my question is why make this out of clay at all? There are faster, easier methods of making that form that would have a much lower risk of failure. If you asked me to make that piece, clay slabs would be way down on my list of possible methods if I was allowed to use a cold finish. And since you did make it out of clay despite the challenges, why stop there and use cold finishes and not fired finishes?
  17. Like
    PeterH reacted to oldlady in Will Acrylic paint damage an electric kiln?   
    molly,  there are lots of things to try in the ceramic field.  sometimes people think that if they speak about why they are interested in trying some experiment that other people might copy that idea so they do not give any details about their plans.
    ceramic work has been done for centuries so it is unlikely that an idea has not been tried already.  if brand new technology is involved, that idea might be new but the odds are that someone has tried that experiment already.   even if the results wound up on the scrap heap (recycle) long ago.
    if you say what you want to accomplish, someone here will probably explain exactly how to do it.  if you are trying fine line drawing, there are lots of ways to do that.  none involve acrylic paint.
  18. Like
    PeterH got a reaction from Studio314 in issues with pink Mason Stains   
    In case it's any help there is an analysis in
    Porcelain body "Audrey Blackman“  https://glazy.org/materials/58805
  19. Like
    PeterH reacted to Hulk in Routing / CNC to form ceramic work?   
    Hi moh!
    No experience machining clay, am recalling a thread here (this forum) on turning pieces using a lathe (not recalling if it was a wood or machine shop model); any road, bein' curious (and on the couch), found

    a five axis cnc milling machine (by Tarus), aye.
    Note the work is being done on damp clay panels, hence chips (vs. dust), which makes some sense, eh?
    Whilst waiting on replies, could you expand on the three and a half inch thick idea?
  20. Like
    PeterH reacted to Bill Kielb in Member Location formatting   
    @PeterH @Hulk

    Work Around
         will insert the leading space.  

    So:
    Location United States - Illinois ends up as: LocationUnited States - Illinois ...........with the leading space stripped.
    whereas:
     location  United States - Illinois ends up as:  Location United States - Illinois ........ and forces the leading space.
  21. Like
    PeterH reacted to Min in Member Location formatting   
    Admin looked into this and at this point of time there isn't a fix for it. For now it's going to have to stay the same, if a solution comes up it will be changed.
  22. Like
    PeterH reacted to Bill Kielb in Safety of ^6 black satin matte glaze as liner glaze   
    Not to worry , spray them with black underglaze and glaze with a durable true matte clear.  True mattes will go from matte to gloss just by adding more silica so you can texture to your taste so to speak. Satin is just a level of gloss or matte if you will, so you can adjust to your preference with a durable true matte and make it any level between matte and gloss just by adding silica.

    Metal marking is more common with abrasive oxides such as zircopax which microscopically roughen the surface and are happy to grind the edge off your knife. Clear mattes quite often don’t metal mark, been trying to mark a true matte cup I have sitting here for the last half hour - can’t get it to mark.
  23. Like
    PeterH got a reaction from shawnhar in Sawdust in my kiln?   
    Found on p5 of https://ceramicartsnetwork.org/wp-content/uploads/2012/08/CA17D_Sample.pdf
    Often, however, it is best to isolate the clay from the fuel so the smoke can reach all parts of the pot and there is no danger that unburned fuel will blanket some part of the pot and keep it from becoming black. Michael Wisner has developed two ways to accomplish this. To fire outside, he stacks pots on firing stands over sawdust, then covers the stack with a barrel. He builds a fire around the barrel, to create enough heat to cause the sawdust inside to smoke. Alternatively, he can stack pots the same way inside a gas kiln, using a metal barrel as a saggar.  I wrap pots in newspaper and then in tin foil, and fire in a kiln just until the newspaper smokes, which I refer to as a “modified saggar firing".
    Trickiest of all is a silvery black surface. This can be encouraged by firing with damp fuel, so Judd sometimes dampens some of the manure in her saggar. If the silvery surface develops, it’s great; if not, the pots are still a rich, deep black. Wisner’s secret to the coveted silvery color is to burnish with graphite.  
     
     
  24. Like
    PeterH got a reaction from cdub in Ceramics in a sauna?   
    Loosely related paper on botijos - porous ceramics traditionally used for used for cooling drinking water in hot climates.
    an ancient method for cooling water explained by mass and ...
     
    PS Even containers for chilled snacks, drinks or towels
    The physics of pot-in-pot coolers https://hal.archives-ouvertes.fr/hal-02408692/document
  25. Like
    PeterH reacted to Magnolia Mud Research in Glaze calculator   
    try the MELTS software for igneous petrology:
    http://melts.ofm-research.org/ 
    If you go down that "rabbit hole", be prepared for an totally different vocabulary than the one used by potters.  
    LT
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