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hanee

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About hanee

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  1. This argument is always something I'm extremely suspicious of, and while it may not be that you intend it the way I read it, it's worth exploring a bit, none the less: Did Michelangelo, Bernini, Canova, Carpeaux, Clodion or Pigalet prefer silicone carbide or cordierite shelves for their wood fired terracottas? How about stacking and properly firing early Indian lifesize clay figures? (most of which were fired by merely making a bonfire right up against the work in place -- highly underfired and yet they've survived 1000 years with outstretched arms with individual fingers making graceful and delicate motions). Where's this box I'm thinking outside of? It seems to me more like a very tiny bubble in history. Definitely a bubble, as its concave, mirror-like surface makes things inside it appear bigger than they are. It causes a sort of historic myopia. Most of the "right ways" to do things these days are simply a list of products to buy (like kiln shelves, electric potters wheels, pug mills) all of which didn't exist a very short historical time ago. I understand we all have to make a living and pragmatism is a totally acceptable philosophy -- but these days we tend to have convinced ourselves our pragmatic choice is *superior*, rather than merely *the easiest thing we can do*. It is a bit sad, though, that compared to most in the past, most of us modern day "makers", don't really make much of our work: in most cases our machines make things for us and then we come in and knit together a few final details. We do all the "important parts" like thinking that we're choosing a shape (among those that our machines make easily formable) or a color (among our 'rich' pallet of lab-engineered, repeatable pigments). This is all said to be the route to perfection and efficiency, yet, oddly, not many seem to be lamenting the supposedly inherent imperfection or inefficiency of work made 100 or 1000 years ago. ----- I would love to learn about some pre-industrial kiln shelves, but so far no one has given any historical equivalent. That makes sense, since it's sort of an absurd engineering problem -- similar to a flat-top kiln or a flat roof that has to handle snow-load. It can only be solved with the really-big-hammer approach of high-technology materials. A free-span dead-horizontal is just not what the materials themselves would dictate, it's a carefully engineered imposition. Like steel beams and plywood. I'm guessing if there were any shelves to speak of they'd have been metal bars, probably cast iron (in the cultures that had the metallurgic technology to support it), and they would wear out relatively quickly.
  2. Hi Neil, In my case, I'm not a potter, nor am I using glazes, nor am I firing to higher temperatures, nor am I stacking regular forms -- I can definitely see how stacking a set of regular forms would likely benefit from kiln shelves, but some of your comments really don't have much to do with the particulars of my stated application. So, I think you've tended to re-enforce the idea that kiln shelves go hand and hand with a need to consistently stack sets of glazed pots efficiently, and thus, they are of more limited utility for low-fire, unglazed terracotta figure sculptures. You've definitely re-enforced the idea that the type of kiln will largely affect how usable it is without (or with) shelves. For example, Steve Mills' "Philosopher's Kiln" really has no need for shelves nor an easy ability to use them due to the shape of its firing box being squat and long to begin with, whereas a very large kiln with a perfect consolidated cube of space would benefit quite a bit from saggars or shelves. Assuming the kiln is built to the type of work you're doing it should be able to be built without a need for shelves, though, I think, regardless of what your particular aesthetic or functional demands are. Really, my ideal would be a kiln the size of a couple busts or a couple figures, since none of my work stacks well to begin with (with or without kiln shelves).
  3. Excellent! Thanks to both of you for the reassurances. It sounds like I can ignore kiln shelf advice I'm reading in my particular application. It was seeming to be a blocker before since some of the kiln building books say "start designing your kiln with what sized kiln shelves you will use." The way I am understanding it at this point is that the kiln shelf usage has to do with the aesthetic requirements of the final product (neatness, consistency) and/or fusing issues at higher temps through either natural (ash) or artificial glazing. So basically, at least in my application, If I can find a way to stack works without breaking them before firing, and if I can work with any consequence of irregular patination where works touch supports or other works (which can be reduced with wadding), then there are no other mystery issues to account for. Perhaps a specific positive on the side of no-shelves is less draft blockage.
  4. As I get towards building my first wood-fired kiln I'm undergoing a bit of both sticker shock and "dependency-shock" with the recommended kiln shelves. I.e. they are both ridiculously expensive and dependent on substantially sophisticated manufacturing processes and materials. First of all, does anyone know what, historically, was used for kiln shelves? If I was going to fire a terracotta in 1650 italy, would there be such a thing as a kiln shelf and if so what would it be made of? My assumption is that works were just loose stacked, as in pit firing. Or, if not that, then simply stacked and supported with odds and ends of pre-fired work. If so, then what makes such high tech kiln shelves necessary then, today, when I am trying to do something as low-tech as wood firing? Does it have to do with current approaches to glazing (my sculptures are unglazed, so no issues there)? Or perhaps does it have to do with vitrified wares cementing to eachother (I'm firing terracotta below vitrification, so maybe no issue there)? Or -- perhaps it is just our modern intolerance of the occasional catastrophic failure (a work low-down in the stack coming apart and those above it crashing down)? Keep in mind my work is irregular shapes to begin with, I'm not looking to stack and fire a set of pots but a bunch of human figures in various poses with out-streched limbs and such. Perhaps kiln shelves are less needed in that case as well (as compared to, say, just some stacked bricks intelligently arranged to support each figure in key places). And finally, if kiln shelves are an absolute necessity for a wood-fired kiln, could I conceivably make them myself, whether with low-tech materials or modern refractories? If I can mix a diy refractory for a kiln wall then shouldn't I be able to use the same refractory, at the appropriate thickness, for shelves. Recommendations, short of buying kiln shelves?
  5. Liambesaw, I appreciate your first-hand experience -- just the sort of advice I'm looking for. My understanding was that the both IFB and fiber are best used as an outside insulation to a mass-based structure for more reasonable cool-down performance and more durable structure. In this case, not seeing how the fiber would degrade much (no direct flame/ash contact, maximum temperature exposure well under its rating, etc). Do you feel that IFB by itself would be appropriate for a wood-fired kiln? Would single-course caternary be structurally sound enough? If so, I could conceivably justify the cost by using it, otherwise I'm simply not sure if I can afford to spend so much. If it needs to be double-course, then I can use cheaper used firedbricks or refractory and do fiber on the outside. My direction, if I chose fiber, would be something like this kiln by Joe Finch: http://potteryandpaintings.co.uk/kilns/downloads/ClayKiln.pdf -- the fact that normal mineral wool is fine up to 1300F or so, I would tend to do less fiber than he used and more mineral wool, since the cold-side of even 2" of fiber will be likely well below 1300F if I'm only firing my sculptures to 1850F. By my calculations this sort of kiln would be one of the cheapest possible while still highly insulative and durable. My other concern is budget as regards exploration -- even if a fiber kiln lasted only 50 firings it appears to me that it would be 1/8th the cost and represent a lot of exploration and learning for low investment, putting me in a situation where I could more confidently know what my needs were and understand the relative value of different options. ... Note this is for unglazed, low-fire sculpture to a maximum of Cone 04 (and more like Cone 08 is fine). Overall most every source for kiln building besides primitive kilns (which is really what I would build if I weren't so energy conscious) seems to be trying to either: high-fire (thus high temp demands on all components and more extreme expansion/contraction), or raku-fire (high btu, very fast, thermal shock to deal with, easy access to get work out). Meanwhile I'm looking for a rather slow, safe low-temp bisque for thick work. I would feel all the engineering would change pretty dramatically if this was accounted for. I'm not actually sure how much fuel would be saved or better results would be achieved using low or no insulation compared to standard recommendations (9" IFB) not when I fire Cone 06 with a slow ramp and slow cool down. It could be that all this fuss about insulation in my particular context amounts to 1/10th of a cord or something much smaller than the amount of embodied energy and cost in all this high tech IFB/fiber/etc. Personally, at low fire temps, I don't see why I couldn't just use a simple mix of fireclay/sawdust/etc as an insulated cob of sort. It would seem to be that it would be easy to just have a mix that begins more refractory/massy for structure/durability and moved to a higher insulation exterior (vermiculite/sawdust/paper) and then a weatherproofing exterior layer. Some expansion cracking issues to design around, but seems doable. I'd rather not reinvent a wheel though if I see no signs of others using the same approach perhaps there's a reason. I'm hoping to get something up quickly and cheaply and learn as I go.
  6. I posted last-year about wood-firing or propane firing for low-fire sculpture. The responses were really helpful and I've spent a good amount of time researching and understanding my options. But now comes the hard part: making actual purchases. While I will be getting into specifics of design shortly, right now the questions I am trying to settle are more on technologies. Cost is a major concern. I have the 21st Century Kilns book and have browsed through a few other sources (Finch, Olsen and Ian Gregory). Something keeps confusing me, though. It seems that a lot of people speak as if firebricks are going to be cheaper than other options, but my experience on pricing right now seems to be radically opposite, when comparing total insulation value. First, for IFB's, the cheapest I can find somewhat locally would be $4 a brick for flats. A guy down the street who is moving and has tons of ceramic supplies is selling his pallet of IFB's at $2 a brick -- but I may or may not get in on that deal in time. Keeping to a consistent metric for the insulation-aspect: most people seem to recommend a 9" wall with IFBs. That would work out to $51/sqft for surfaces with new bricks, or $25 for this special deal. Now, for ceramic fiber blankets, my research indicates that 4" at 8# density would be roughly equivalent to 9" IFB in terms of insulation value. There are plenty of sources for very affordable fiber: ceramicfiberonline.com for example has 2300F 1" fiber at $1.48/sqft. Since I'd need 4" of that to reach the same level of insulation as the 9" IFB, that's $5.92/sqft. Even the highest price fiber blankets I can find work out to $15/sqft. So, by my math, in my market, apples-to-apples new-to-new comparison: IFBs are 8.6x as expensive as ceramic fiber! Is there something I am missing here? How could anyone on a tight budget justify IFBs over ceramic fiber when considering insulation alone? Is the market changing compared to when these books were written or, am I getting some math wrong, or perhaps am I not finding well priced vendors? Since with either IFB or Ceramic Blankets a mass-based castable refractory or hard brick interior layer would be ideally recommended for wood-firing, the fact that the IFBs are structural seems to not really yield any advantage at that level. And reusability is the similar on each. The only difference is durability, in which case neither are great performers relative to hard firebricks but the IFBs win -- but not so much that they will last 8.6x longer! or even 4.3x longer, especially if both are placed behind a hard layer and the firing temps are low-fire to begin with. Now if it would be acceptable to just use a single layer of IFB's for the firing chamber, then I could see how the IFB's do double duty compared to having to create a rigid form over which to drape the blankets -- but then again, people often manage to get away with using things like old trash cans or hardware cloth to support ceramic blanket structures. Also I've heard the argument on this forum that ceramic fiber blankets are too toxic, but I fail to see how that's of relevance in an outdoor-built kiln where the blankets are sandwiched between an inner and outer layer -- and if there is still relevance than it appears to me that, at least for low fire, there are safe blankets: ceramicfiberonline.com has a "biofibre" that is supposedly nontoxic and rated to 2012F instead of 2300F (I'd only be firing up to 1850F anyway).
  7. Thanks for those excellent starting points! I will dig in on them. Yes, if it was possible to custom build the kiln to the project that would be ideal -- it would probably tie me to propane and technology more, but it would also probably be very fuel efficient and possibly allow me to fire things that couldn't be fired otherwise without a great deal of infrastructure if I had to build a conventional firing box.
  8. I've been a renter and have moved around most of these years so up until now I was never able to consider building a kiln. But after many years of dreaming, we bought land last summer and built a small house and I'm now ready to start planning my studio and kiln. Fortunately (or unfortunately), depending on your perspective, we are off grid. So electric is off the list, as are any significantly-drawing electric controllers. We also have plenty of wood resources (13.5 acres). I'm a bit of a purist so I'd prefer to do wood firing, but it might be wiser to build an initial propane kiln to get started and migrate towards wood through experimentation. As for my firing needs. I'm a figure sculptor (my website is at http://haneebirch.org -- though my work has all been on hold for the past 6 months ever since we took the leap on buying land). There's a few requirements that come from that. 1. I only need to bisque fire (cone 06-05). That means my kiln can be designed around only needing to reach those lower temperatures. (Though in the long term I may start trying my hand at slip casting, which woudl technically open up porecelain to me I still think I would tend towards earthenware as I'd rather keep with the lower BTU and the earthier tones) 2. I need some flexibility in size. Long term I may want to try firing some lifesize full figures, but short term, I need to easily be able to fire half-size work (roughly 36" in one dimension and, say, 24 in the other) and busts. 3. I will likely want to have a rather controlled ramp-up and ramp-down though I am comfortable making my bodies more shock proof if needed (I've used raku clay in the past but that was when I did much coarser work than the work I do now). That said, I've never had a sculpture break in a kiln and I have used everything from raku bodies to completely grogless clay, and have fired plenty of things with air pockets and uneven, very thick sections (or solid). I also intend to be exploring base-bodies with heavy straw/planar-shavings/hemp, and firing large solid sections with that mix (which I believe should fire rather well as a ventable but solid core). So, I'm looking for book recommendations or online resources or personal advice as to good designs to consider. Wood firing, as I said, would be very mcuh ideal. Cost is a major consideration and I also prefer to use very little technology. Within the rocket mass heater community some people have had success with hand built sraw-clay-vermiculite fireboxes instead of insulated firebrick, ceramic fiberboard, blankets, or cast refractory, so I'd like to explore some eartheir low-tech options but I'm not sure if similar explorations have been done in the ceramics world Mainly, to start, I will probably just need the quickest, simplest, cheapest cone06 propane-based kiln I can put together but I'd love to be pointed to some dreamier wood-fired options. Also, I live in a cold winter climate (Penobscot, Maine) -- not sure how reasonable it would be to fire outside and even if I could manage to fire the kiln on a negative 20 degree day, I'd rather not waste the precious heat so designing the kiln for firing indoors (with proper exhaust and make-up air) would be ideal, but not if it made the design much more difficult to acheive. Personal recommendations? Good books to look into? Websites? Thanks!
  9. Interestingly, in the permaculture community there appear to be people creating wood-fired cob forges and rocket-stove forges, which may be a starting point for a design that's not tied to firebricks. Charcoal is also another option if need be for more consistent results, but that's another off-site input. If I do end up exploring a partly cob-based kiln I will definitely report back any results (or failures). It seems like experimentation may be a better choice if no books show up, so long as there is no cost involved other than basic materials.
  10. I've heard about converting electrics (whether to gas or wood), but that's another investment to make (though I understand picking up used can be the chepeast way to get good firebrick), not to mention it's suddenly bringing a lot of needless technology and ugliness into what is essentially a primitive endeavor... I would prefer to do something more traditional... part of the desire for wood-fire is because I don't want a lot of external inputs to make the process work. Ideally I would use some (perhaps double-walled) cob-oven type design and not bring any off-site materials (no firebricks)... My suspicion is that 3/4ths of the design choices I see being made in many of these kilns comes from the desire to fire at high temperatures, to fire quickly, or to achieve reduction or ash effects. The raku wood-fired kiln designs I am finding appear to at least be build for the lower temperature, though they seem to usually be designed to achieve that temperature rather quickly. Seems strange to me that if everywhere other than asia rarely fired much above 1750F and rarely used anything like firebricks, and everywhere including asia was without electricity or propane, all the way up to a few hundred years ago, then there should be many established repeatable designs for a reusable kiln for small loads. Perhaps an old out of print book. I have the Cardew book and that's certainly a starting point but he's building large and firing hot... I can extrapolate, certianly, but I'd think there'd be some historical or revivalist book that would be more fitting.
  11. I'm exploring making a wood-fired kiln, but all of the resources I am finding are for firing at much higher temperatures than I need and also for generating ash effects. Here are my needs: - Firing to somewhere between 08-04. Traditional terracotta. - A reduction environment is not needed (and probably not wanted) -- this is for figurative sculpture. - There will be no glazes, this is just bisque firing. - Firing box would have to be able to contain an object of maximum dimensions of 12x18x36, oriented in any direction. - It would be ideal if I could keep the design and fire box as small as possible as it would be preferable in every way to fire small amounts more frequently. Basically I'd want to recreate the firing properties/technology of a 16th-17th century terracotta kiln, but plan size scaled down to the minimum possible size for a small cache of works. Any recommendations on a book that would cover the principles I needed to know (or have ready-to-go designs) for these needs?
  12. I am a figure sculptor (haneebirch.org/artwork -- out of date, but gives a basic idea), and I've worked over the years in a variety of materials, both clay and non-clay. I've been steadily working towards more detailed work in the past couple years (none of which is on my website yet), and while I love the feel of a traditional red earthenware body, I am sometimes feeling like I am at it's limits (or rather, my limits!). I'm trying to explore which clay bodies will work best for both the early stages where supple gesture and the ability to make quick, dramatic changes to the pose, is the needed feature and the latter stages where things like modeling a tiny 1/3rd scale nostril or eyelid, or lightly smoothing in a controlled manner that doesn't merge forms too easily... Anyhow, introductions aside. I got a couple boxes of WED clay (Laguna EM-217) about a year ago. At first the stuff seemed almost like a bad batch it was so intensely sticky (and I usually like sticky products, as I used to work in wax). I still am not sure if I got a bad batch, but I have learned to work with it. It seems exceptionally good for finely controlled form at the later stages of sculpting, but at the early stages it can be a real sticky mess compared to a good terracotta body or the raku/sculpture clays I've used in the past. I am trying to understand what exactly is different about the clay. All the public information on it always emphasizes the slow-drying qualities (and the fact that it's not ideal for firing, but can be fired nonetheless) -- I don't particularly care for it's slow drying nature as I work quickly, but, what I notice and appreciate more than anything when using it is that it has a certain density that resists pressure. For example in my standard laguna terracotta body (and most similar clays I've used from other manufacturers), there seems to be a "spongy" quality. Pushing in one place deforms other places and it is so soft, even when at the equivalent moisture level, that crisply modeled forms easily round over if touched indelicately. On the other hand, WED holds detail and you can easily run wet cloth over a sharp form and only take a hair's breadth down off the sharpness. It's density is more similar to raku clays I have used (which I believe usually are a stoneware base), but it's plasticity resembles most some 'wild' clays I've dug which I believe were extremely carbonaceous -- almost completely unworkably plastic unless in a rather more-dry state than I would habitually use a clay at. I'd like to either locate a similar clay to WED, that doesn't have substances added to slow drying, and that is perhaps a tad less sticky or "fat" as they say, and that ideally fires to as-strong a product as a terracotta body does at cone 06-04. I will mostly be using it for casted works, but it's nice if I can use the same body for firing when need be. Any thoughts on what the constituents might be, or at least what types of clay might be similar (very-dense/extremely-plastic)? I am guessing (based on some research and my own very limited experience) that it is a stoneware base (dense) with a lot of ball clay (highly plastic). It also has a bit of a chemically/bleach smell when new which disturbs me -- perhaps it is whatever "retarder" is added to slow drying. It seems to also have a far, far narrower range of workable moisture levels than my usual red terracotta, if that's another clue. (In the UK a similar product appears to be sold as "Potclays Modelling Clay" -- https://www.potclays.co.uk/studio/products/5242/modelling-clay-157-1150-1100-1280c )
  13. @Marcia Selsor -- Thanks for the book reference. Books are usually how I learn these things. Correct, the Bacchus I believe is a unique original. Most the works by the bigger names in that period are, but books always mention lesser works that were mass produced and a few are specifically credited as cast. @Sputty -- Wow, thanks for that video. Extremely helpful. I am curious since you seem to have some historical knowledge on this: many of my books seem to indicate press molds were used rather than slip cast molds. Slip cast seems like it would be far easier (since you can cast enclosed forms without having to later joint them). Is there any reason that a press mold would be avantageous (I can only think of disadvantages) or is the slip technique just historically more recent? I am still debating just how worth-it doing terracotta casts would be -- obviously it would be a labor of love; I'm not sure if the market will really care to make as much of a distinction as I do between some fake-bronze resin cast from silicone and a ceramic piece assembled and hand-finished from piece molds. Anyhow, your video is an invaluable aid as far as some directions on how to go about it, if I do decide to for some of the simpler figures. I do believe silicone could work for press-molding if done just right and it would allow a two or three peice mold in most cases -- but obviously it wont work for slip casting. I will have to experiment to see which method, all said and done, is the lowest labor for equal results. The purist in me would prefer a plaster mold, if I can acquire the requisite skill. Thanks again for the video link. @Chilly -- I only know of one places that I believe might do slip cast lawn-figures and the like, but it is about three hours away. I will ask to take a peek the next time I am near. Overall, it seems a good first step would be to chose one of my simpler figures and mold a version in which most of the smaller, more complicated undercuts are filled in to reduce the total number of pieces needed to piece mold, then cast, and rework the undercuts and complex areas. As my molding capability increased I could mold more pieces accurately and re-work less. Obviously this is a very hard-won additional skill and it would be better to take it slow and steady in terms of increasing complexity if I'm going to rely on it as a primary tool of production.
  14. I'm a figure sculptor who has worked in the past in direct-terracotta (http://haneebirch.org/artwork). I have a new body of work I am in the process of putting together, and for practical/economic reasons I am going down the road of mold-making and casting instead of direct work. Unfortunately, this usually means moving from terracotta to plaster (or worse, plastics and the like). I don't mind plaster but it's hard to touch up and doesn't have much value to most people -- ends up needing a patina, etc. So... What I'd like to do is find out how to cast terracotta figures as was commonly done in the 17th and 18th century. All my catalogues of figure work from that time period always refer to cast-terracotta being fairly common. But, nowhere in modern method books have I ever run across anyone who seems to see such an undertaking as even conceivable. Take this figure by Clodion for example, in the Met's collection: http://www.metmuseum.org/art/collection/search/200559 So, I do have some experience with mold making, but I've never been the greatest mold making. I seem to be competent at waste molding (except I've never gotten a great release agent recipe that really works consistently, seems like sometimes I get lucky and have perfect release, other times something in my application process must fail), and am capable though not exactly confident with my brushed on silicone molds. In my limited mold knowledge I am guessing this peice by Clodion was press-molded, in a multi-part piece mold. Still, it's hard to comprehend how exactly that would have been done, with the bird wings and many undercuts. For myself, my figures are fairly unadorned but the poses are still complex. I can imagine that I could ignore many of the undercuts, cast a rough form, and then I could easily clean it up, add depth, put the undercuts back in. But still the piece mold for a basic figure of non-trivial pose (say, http://haneebirch.org/artwork/chair-no-1 seems beyond my comprehension). Even chopping the figure into separate parts and re-attaching doesn't simplify it all that much, and I'm unclear on how exactly that would be done anyway. So is there anyone who would know of any book or person that could describe all the technique needed to press-mold or slip mold that Clodion figure or the figure I referenced of my own? Is there some alternative technique that I am not aware of that makes this all a simpler proposition than I thought? I have tried press-molding in a silicon mold, and, to some degree, it worked, but how to cleanly joint the pieces and how to control for moderately even drying seemed unclear (though perhaps with enough experimentation). Anyhow, before trying to blaze my own path with modern materials, I'd really ideally like to find a source who can make entirely clear how exactly this was commonly done in the 18th century. Thanks in advance for any information.
  15. Highbridge, that's really fascinating. If we're both understanding this particular diagram correctly that would mean that the reputable sources I'm reading are only speaking of grogs impact on shrinkage/drying issues because it perhaps has no significant impact on green strength in the concentrations we usually use it. Do you know when they say % are they usually referring to by-volume-% or by-weight-%? I recently got a copy of Daniel Rhodes' Clay and Glazes for the Potter, based on recommendations on this forum and the only references to grog are in terms of shrinkage/drying. Seems counter to everything I learned in my figure modeling classes way back when, but I expect potters know more than sculptors on this one. JBaymore, the kind of strength I'm looking to optimize for primarily is that of an outstretched limb. Secondary to that is compressive strength (say, all the weight of a figure on one leg). Both in the early-green state (i.e. working consistency). Empircal testing is great, but it's nice to have some knowledge to give a bit focus to otherwise random permutations, if such knowledge can be had.
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