When I began working in ceramics all those years ago (the 1970’s!) I can recall being disappointed, first in high school and then in college, at the “lack” of color in the available glazes. We all had our boxes of crayons bursting with color, and even the cheapest mass-produced consumer goods were glaring with color. Even today, consumer goods (even foods) are bursting with artificial color. We inhabit mostly a built environment (how often are you out in nature?) where a cacophony of accidental color prevails. For example, I’m thinking of a very tastefully designed lounge, with all the furnishings and carpets and such color coordinated-inhabited by people sporting all kinds of colors, carrying bags and things with even more crashing colors that were most decidedly not a part of the designer’s scheme. I think we learn to ignore all these clashing colors as some kind of self-defense mechanism. I have to admit, it could be age. But it could also be looking at lots of great pottery-Bernard Leach, Shoji Hamada, Michael Cardew, Phil Rogers, Matthew Blakey and plenty of works by unknown potters in museums-I’m coming to appreciate the palette of winter. It’s like a palette cleanser for the eyes. For me, the browns aren’t neutral. Some are russet, some cool, some tawny, and these browns are punctuated (some days) with blue sky, and evergreens wearing their dark green winter coats. And when it snows, the blue sky is replaced by white, silver and a range of greys as varied as the browns they cover, to varying extents depending on how much it snowed. Don’t get me wrong, I still love the deep saturated colors of medieval stained glass, for example, but I’m also appreciating the subtle symphony of colors that winter offers. Even as a child I loved drawing bare trees, fascinated by the spooky dark trunks and branches, the more gnarled the better. But the NCC East 40 is mostly meadow. The mountains, ocean and even forest that I always tended to associate with “nature” just are not there. Much like the winter palette of colors, which I’m enjoying more and more, I’ve come to appreciate the subtlety of the forms of the meadow. Today a new revised reprint of Bernard Leach’s classic tome “A Potter’s Book” arrived. This edition has color versions of most of the pottery examples, and they are very much in keeping with the winter landscape.
Right now I’m perfectly content to inhabit the colors of winter.
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I knew I wanted to use gold on my ceramics before I even knew why! Real gold will evaporate, “volatilize” is the technical term, if exposed to the high temperatures needed to fire the clays that I use. I confirmed this the hard way, three years ago I embedded some tiny bits of gold foil around the rim of a pot, and even in the preliminary “bisque” firing (not as hot as the final glaze firing) the pot emerged from the kiln without a trace of the gold. You’ve probably seen fine china that has gold trim or accents, for example around the edges. The way it’s done, is that you glaze and fire the whole thing first, without the gold, at the usual high temperature. Then, you apply the gold and fire at a much lower temperature to “fix” the gold permanently onto the ceramic. This is what’s called an “overglaze,” and what I finally got around to doing! With wood firing, you can’t control exactly how anything is going to come out, and honestly the serendipity of it is a huge part of the attraction. But sometimes a piece comes out of the wood firing and, well, needs some help. Well, I had some pieces that just needed a little oomph, a little spark, an accent.Two of them had a lovely, ivory colored satiny glaze surface; but they were to subtle, they needed an accent, some pop. On the other end of the spectrum, I had a piece with a kind of mottled surface, mostly quite dark. Finally, I had a piece that had quite nice “flashing”-effects of the fire on the clay, which highlighted the sculptural form really well-but the surface was quite dull and matte, no shine. Opening up a wood kiln is like unwrapping Christmas presents-you may have an idea what to expect, on the other hand, you can get some real surprises! What I find the most strange, is how difficult it can be to figure out if the surprises are good or bad. It can take months, even a year or more to really “digest” the serendipitous effects off flame, wood ash and the myriad variables of the firing. I had two sculptural, medieval inspired vases in the kiln, both had a salt-white glaze, and came out weirdly brown speckled. My first response was yuck, not what I had hoped for-and not what I had got from the same clay and glaze combination in Previous wood firings in the same kiln! In fact, there was another vase in this firing, same clay, same glaze, but it was a re-fire from the previous firing. In that previous firing, there were parts of the kiln that just didn’t get hot enough to properly melt the glaze. But this time, that pot came out with a kind of lovely glow-I’m so glad I re-fired it. But what of the two speckle monsters? Hmmm. Not so sure about those, have to sleep on that for a few months. Then there were the mug re-fires. These were all made from “C Body” East 40 clay, and had been through a 6 day anagama firing this past October. They too must have been in cold spots in that firing, the glazes were rough and underfed. This is a clay I formulated less than a year ago, so I’m keenly interested in putting it to the test in every way possible. I had pieces in the Peter’s Valley anagama firing, in locations of the kiln that got up to cone 11 (the clay was formulated for cone 10) and there was no trouble at all. No flaws of any kind in the clay. There were also no flaws after the October 6 day anagama firing-but this re-fire kind of “fried” them, since they were located in parts of the kiln that overshot the firing range of this clay body. Let me explain. We used cone packs that had two cones below our target, (cones 8 & 9) our target cone (10) and a “guard” cone of 11. In the photos, the order from left to right is 8,9,10,11. In the first photo, you can see a perfect 10.The number 10 cone (third from left) is making a perfect arc, the tip down to the level of the base. There is daylight under the arc, as there should be. By contrast, the lower temp cones 8 & 9 are no longer an arc, they are a puddle, and cone 11 is only beginning to bend. In the second cone pack, there is no daylight anywhere under these cones, even cone 11 is a melted puddle on top of the clay that held the cones in place. What this means is that in that section of the kiln, we blew past our goal of cone 10, and because 11 is a puddle we must have actually hit cone 12. I found out the hard way the upper limit of the C body clay; it was fine at cone 11, but cone 12 was just too much. One of them cracked early enough in the firing that the glaze hadn’t melted yet, since, the glaze healed over the crack completely. Another had little bloat bubbles. The work had been over-fired enough to become so brittle that several of them had chips that broke off the bottom where there was no glaze to support the clay. To be fair, they were really close to the firebox, which hit at least two cones above our target, as explained above. And in spite of the flaws in some of them, others have no visible flaws and they certainly didn’t melt into a puddle or even slump, which can happen when a low-fire clay is high-fired. I fired an odd little piece I had done as a demo for texturing slabs, and making a draped form with visible slab joins from them. On the inside I sprayed on the East 40 ash glaze (that I formulated) in a fairly thin layer, and the outside was a combination of two different shinos and a salt white glaze and a little bit of the East 40 ash. For a little throwaway pot-I was going to just recycle the clay after the demo, but decided to keep it to just to experiment with glazes-I’m surprised at how good it looks.
In short, the work I cared most about-the medieval inspired vases-came out just whatever, while the piece that took me 10 minutes to make came out great. Or at least that’s what I think today. Maybe I’ll wake up in 6 months and have a totally different opinion. Please comment and let me know what you think! Please note: these videos take a while to load. (Having technical problems and don't have enough hours to throw at solving them right now) The burn ban was finally lifted, and on December 18 we finally began the firing. The two anagama firings I did in August and October went on for 5-6 days; but this firing was scheduled to be completed in just over 24 hours. To get the work “fully cooked” meant that we had to actually reach higher temperatures in the kiln than would be the case if we were firing over many days. The cones behind the removable bricks were our only way we could be sure when the work in the kiln was fully “cooked.” The heatwork needed to achieve cone 10, our goal, is considered to be 2,381 degrees. That level of heatwork can be reached by more time at over 2,100 degrees, but for a one day firing we were going to need all 2,381 degrees to get cone 10 to bend over. Gabby Gentile and Connor McGaughran (my student worker at ESU) had been there since 2 in the afternoon, and stayed with me well past their points of exhaustion until after Dave Graham (Kiln Building Guru) was able to join me. With two fireboxes needing to be stoked every few minutes, this was a skeleton crew. It was after midnight that Gabby and Connor finally went home, and it was just Dave and I for the rest of the night, until the end of the firing the next morning. I took the left firebox, and Dave the right. It’s crazy how kilns have a personality, and how two fireboxes that should be identical, one right next to the other, can behave so differently. The left side of the kiln runs colder, the coals don’t burn down to ash fast enough, so the left firebox can get so choked with coals that it restricts the needed airflow on that side. How much, what size and what kind of wood to put in, and when, are decisions that are constantly being made. You don’t just chuck wood into the kiln and hope it works; this too is an art. Pine combusts faster, but doesn’t have the staying power of hard wood, it’s kind of like a sugar high, you either feed soft wood constantly or it can crash. Hard wood can actually make the temperature drop while it’s trying to combust. Likewise, the thinner the wood is cut, the faster it catches fire-and burns out. Getting the right mix of types and sizes of wood, how much room you leave open in the firebox, how often you stoke-all this has to be right, or the kiln will let you know. There’s a wonderful “roar” when a kiln is really hot, and it’s happily digesting just the right amount of wood. The night was beautiful. It would have been cold being out all night like that, but the kiln generated so much heat that being so close, I didn’t need most of the layers of clothing I had brought. The wind was going in the right direction, I think it actually helped us. Pyrometers that measure the air temperature in the kiln are not terribly accurate at the higher temperatures, but they do let us know if the kiln is getting hotter or cooler, which is critical information for figuring out when to stoke for example. As the kiln heats up, everything wants to expand. I’m glad Dave was there when one of the steel tie rods holding the kiln together popped under the pressure! Wow, that made me jump. He had just replaced the tie rod above the one that broke, and assured me it would be fine. You could see the other tie rods bow with the pressure the kiln was exerting as it expanded, but they held. Even if we hadn’t had the pyrometers, as in olden times, you can really tell when a kiln gets up to those higher temperatures well in excess of two thousand degrees! At 9 something in the morning, Cone 10 had made it’s perfect arc on the top right, and both cone 10 and 11 weirdly were bending together on the bottom left; we got to our goal. Once we reached our cone 10 goal, we stuffed the fireboxes as full as we could get them, then shut off all access of air to the kiln. Kilns go crazy when you do this! Any tiny sliver of space, around a brick, around a door, the flame tries to reach out, gasping for oxygen. That’s when you walk around the kiln-any gaps anywhere become really obvious with flame shooting out of them! The “door” of the kiln is temporary, rebuilt for every firing, so flames shooting out from there are not a problem. But if places that should be tight open up, this is when you find them. The fire just burns itself out, smothers-then you have to wait, and wait, for it to cool down. The bigger the kiln, the better insulated it is, the longer it takes. This post is already way too long, so you have to look at my next post for the unloading!
A delightful part of my part-time job as Manager of Ceramics at the Northampton Community College (NCC) East 40 is firing the wood kiln there! I had fired that kiln a number of times before, but for this Fall’s firing, I took on more of the work than in previous firings. I made the cone packs, for example, and made more of them than we had ever used in a single firing. Cones are scientifically formulated to bend over at very specific levels of “heatwork.” Heatwork is a matter of both time and temperature. The example I always give is lasagna. The oven may be 400 degrees, but if you only leave the lasagna in for five minutes, it’s not going to be cooked through! On the other hand, even if the oven is only 350 degrees, if you leave it in for 40 minutes it’s probably going to be fully cooked. Cones measure to what degree the ceramic is “cooked,” much like how a meat thermometer measures the temperature of the meat itself, not just the air in the oven. It was the first time I actually got to load a wood kiln, which takes a surprising amount of skill, not to mention hoisting really heavy silicon carbide shelves into place. All the hours I had spent watching others load wood kilns was invaluable. The idea is to understand how the flame moves through the kiln, and much like playing pool where one ball bounces off another, you want to bounce the flame onto all the pots, ideally send the flame everywhere, reaching every pot without restricting the path through the kiln. No pot can touch, or even get too close to touching, yet you have to do a kind of Jenga where you get as much work into the kiln as possible. The way ash moves through and lands on the work is another consideration. Suffice it to say it was an honor, and I was holding my breath that certain decisions I had made would work out! For example, Kelly Allen noted that no one had ever put the center shelves as far to the front as I had. Yikes! I was hoping for better flow through the kiln, more ash, but what if it just meant that the work closer to the front door didn’t get hot enough? Gulp. The door for the kiln gets built for every firing! First, the bricks. I actually really enjoyed custom fitting the last brick at the top of the arch, you can see it’s a lighter color than the bricks next to it. In previous firings we had done two bricks that stick out beyond the others, so you could remove them and see the cone packs strategically placed in the kiln for that purpose. For this firing, in addition to the two “peep” bricks, a third one with a hole in the middle was set up as a “blow hole.” Long story short, when flame is no longer coming out of the blowhole, you know it’s time to stoke. After the bricks were in place, Gabby Gentile (professor at NCC) and I “mudded” the door, which is pretty much like it sounds, although we used wet reclaim clay, not the kind of mud you have in a garden. Nothing like hands wet with “mud” in the winter. Then, for extra help so not so much heat escapes from the “door,” a special high-temperature cloth that looks like cotton but is not flammable, supported with a wire mesh was placed over the door. The pots were all loaded, the kiln was ready; but we had to leave it like that for weeks waiting for the burn ban to be lifted.
Even without the added eyeballs and horns, the anagama kiln at Peter’s Valley would look like a dragon. It only gets fired once per year, it takes a lot of wood and a lot of people power to fire this 57 foot long kiln-and that’s exactly what I was up to for this past week. As I write this, the kiln is cooling down, I will post again after the unload which is coming up this Sunday. I worked nights, and hung out during the day as much as I could when I wasn’t sleeping. The workshop was led by the Tara Wilson, an amazing artist with a trove of woodfire experience. Charlie Lid was on overnights (among a lot of other things), a veritable brain trust who has fired this kiln 22 times and made repairs to it. The staff at Peter’s Valley is awesome, all in all it was a great group of people. From loading to finishing was all interesting, but my favorite part was the overnight crew firing the kiln. Each night got hotter, and the last night was just nothing short of magical. We were giving the kiln exactly what it wanted (with Charlie’s interpretations) and it responded. In a few hours, we side-stoked over 900 pieces of wood, and that not counting what was put in the main firebox at the mouth of the kiln. There was music on, and all of us at some point were literally dancing; there was so much joy, we were dancing with the kiln. It’s an experience I will never forget. It’s hard to come up with words that describe the sheer power and elemental force of the flames within the kiln, that on that last night refused to be contained by the lids on the stoke holes, or the damper at the end of the kiln. Note that in the above photo and video, there is nothing “open” on the kiln; there are lids on the stoke holes and a big solid damper covering most of the end of the kiln-but the fire was so powerful that after we would stoke, it would erupt like a volcano from the slightest of gaps.
In my first post on my new series of Medieval inspired ceramics, medieval-inspired.html I wrote that “So far only a few of these pieces been glaze-fired.” I think one of the strengths of this whole series is the interaction between a traditional thrown form with decorative/geometric/abstracted elements and incomplete figurative elements. An essentially one-color glaze keeps the ambiguity and imaginative leaps that the viewer can enjoy. I have come up with two strategies for making the glazes have some depth, variety and interest without getting contrived looking; local (and sometimes wonky) materials and wood kiln firing. As you can see from the vase above, glaze is not always going to hugely change the look of the piece. Even with the different background, lighting and point of view, this vase didn’t change its essential character when glazed. I formulated the glaze that I used featuring rock that I picked up off the side of route 611 in Easton. You might think that I could have used just any white glaze; but look closely at the comparison photos below. On the left, the vase was glazed with the glaze that I inherited in the ESU studio, with all commercial ingredients. On the right, another vase glazed with my rock glaze; I know it’s not a huge difference, but I prefer the rock glaze. So on the one hand, the glazing doesn’t necessarily radically alter the look of the piece from its pre-glazed state. But on the other hand, the glaze-and how it’s fired-really do matter, and give not only practical advantages like hardness and waterproofing, but improve aesthetics as well. The vases above were fired in an electric kiln; the first post I made about this series showed work that was fired in a one-day wood kiln firing. Wood kiln firings can have many serendipitous effects, between wood ash landing and melting onto the work (that was probably how glaze originated) fire hitting the work and the reduction atmosphere which causes both the clay and glaze to achieve different effects. The longer the firing, the more wood ash you are going to get, which is one of the reasons I’ve held off firing a number of my pieces; I will be taking the Anagama Wood kiln firing workshop at Peter’s Vally next month, where I can bring 30 pieces! Whether I’m using rock glazes or wood kiln firing (or both) my goal is the same; I want natural effects, not contrived painting/coloring.
Vase made from the new clay body featuring East 40 clay. You can see the clay with no glaze at the bottom, and where I did strokes of wax resist as seen on the view to the left. A glaze featuring the East 40 clay was used at the top of the pot, you can see it's darker than the glaze below the neck of the pot.. As promised, some results from the test kiln firing. After making the part 1 post, I realized that it was just too technical for a blog post. I reached a kind of crossroads where I realized I needed to create a section of the website for technical information. If you want something more in depth than this post, go to my new Ceramics-Technical page, and the pages that branch off of it. The little test kiln did reach cone 10 (approx. 2,381 F) but not without a battle of many hours in the sweltering heat. Luckily, it was worth it. The firing gave us really critical information; how will the new clay body behave at high-fire temperature in reduction (oxygen starved) kiln atmosphere, which is how we fire the wood kiln? And, how will the 25 glaze recipe variations with the East 40 clay look and behave on the new clay body? Overall, the results were a smashing success. Both clay body, glazes, and the way the glazes look on the clay body passed with flying colors. Again, I'm not going to go into all the technical results here, but I do want to show you some of the highlights of what came out of the little kiln. In the test bars above, you can see the color of the clay with no glaze for yourself. In addition to the tile in the test kiln firing, the dark one at the bottom of the photo, Gabbry Gentile was kind enough to fire the one on top in the electric kiln up at the ceramics studio in Penn Hall on the main campus. I formulated this clay body for high temperature firings like we do in the wood kiln at the East 40; the real shocker, was that this clay body works at the medium range temperature used in the studio on campus! I won't go into the technical details here, but suffice it to say I was honestly shocked at how well this clay performed in an electric kiln at mid-range temperature! Ash glazes are supposed to show dramatic drips; the trick is, you don't want them to run off the pot. This test tile was photographed on its back because of sun glare, but it was standing up on vertical when fired in the kiln. The pleasant surprise was that all the variations of the ash glaze stayed up on the tile, none of them ran off the tile at the bottom which is a big problem with a lot of ash glazes. Many ash glazes can only be used at the top of the pot, they are so runny. This was the runniest variation, and even it didn't run off the tile. Long story short, we already have usable glazes based on the East 40 clay and wood ash, and they work great on the new clay body! Above is the simplest glaze recipe I tested-and my favorite result! The drips are less dramatic without the eggshell. It's such stable glaze that I can see using it on an entire pot, not just at the top for a drippy effect. The color comes primarily from whatever is in the East 40 clay, educated guess, a lot of iron.
Getting back to the vase at the top of this post, the dark part at the top is the same as the tile above, except there is an addition of copper oxide. The pot was first dipped in a glaze we had on hand from previous wood kiln firings, we wanted to see how it worked on the new clay body. The red you see, especially on the view to the right is actually from the copper-rich glaze I was testing at the top! All in all, we got lots of very helpful information from the test kiln firing. In all honesty, I didn't expect this much success in a first time at full-temperature firing! Interior of the wood kiln at the Stahl's Pottery. You can see where the flame, heat and smoke came up from the 4 fire boxes in the floor; the pottery was put into other plain pots called "saggers" which were stacked floor to ceiling before the kiln was fired. 16 vents in the roof provided a draft to the chimney. I had two main reasons for going to the bi-annual Stahl Potter festival on June 15. One, I found out James Chaney, who I studied with 1978-80, was going to be there and I just had to tell him in person how great his instruction had been, and how I was building on it all these years later. The other of course was to see the historic pottery, and in particular the wood burning kiln.
Not long after I met the man who has now been my husband for 25 years, he asked me what kind of architecture I liked best. It’s not a question anyone had asked me before, but my pause was under a minute; Victorian Gothic. What might practitioners of Victorian Gothic such as A. W. Pugin or John Pollard Seddon, for example, possibly have to do with a Pennsylvania Dutch Pottery-or Colonial Revival for that matter? Yes, I know this seems very fractured, but it was the trip to Stahl’s Pottery, and reading the book “Stahl’s Pottery of Powder Valley” that connected the dots. My mother despised all things Victorian and idolized all things colonial, so that adds a family historical twist to this aesthetic conflagration. Let me begin to unpack this aesthetic cacophony. The book has a chapter “Arts and Crafts and the Colonial Revival” and the “Arts and Crafts Movement” was invoked on multiple occasions as I toured the pottery and museum. When I think “Arts and Crafts” I think of 19th century and especially British artists; William Morris and Edward Burne-Jones for example, and if American, maybe Gustav Stickley, not of Colonial American revival. But there are commonalities, and my visit to the Stahl pottery got me thinking about them-and my own heritage. It’s easy to think of any revival, be it Victorian Gothic, Colonial or Arts and Crafts Movement, as an imitation; as something less-than the original. But William Morris, whose designs are still popular, did not simply copy older prototypes-he made new designs for a new age, an age that keenly felt the loss of the individual craftsman in mass-manufacture. (It’s a bit mind-breaking that mass manufacture is overwhelmingly how those of us in the twenty first century have ready access to his designs.) And that was the big epiphany-that these “Historiated” styles, when done right, are new inventions originating out of the needs and circumstances of their own times, not less-than imitations of something that is done and over. The Stahl brothers learned pottery from their Victorian father. In the early twentieth Century they shut down the pottery they inherited/tried to carry on from their father, because they couldn’t compete with mass-manufacture. But they opened their own pottery three decades later because the values of the Arts and Crafts movement begun in the nineteenth century had taken root here, in the twentieth century, and the literal value of the kind of work they had done for their father had multiplied. In the midst of the Great Depression no less, the Stahl bothers opened an old style pottery with wood kiln, what is now the Stahl’s Pottery Historical site https://www.stahlspottery.org. I didn’t see my mom’s fascination with the colonial as more than her personal taste; I didn’t see it as part of a larger historical phenomenon. My mother seldom could use the word “Victorian” without the accompanying adjective “monstrosity.” (I suppose my way of rebelling against my mom was a Victorian aesthetic.) I was missing the through lines, of Arts and Crafts, Colonial Revival and my own aesthetics. The Stahl brothers weren’t imitating the work of previous potters; they were doing their own work. The interesting thing with arts and crafts is that when you do things with your own hands, it’s actually hard not to put yourself into what you’re doing, even if you’re using traditional materials and techniques. And those who pick up those pots, or look at those paintings or wear that hand knitted sweater etc. see that human element, which only becomes more precious the more impersonal products become in our society. This summer I am working to formulate glazes and a clay body from the local clay dug from the Northampton Community College (NCC) East 40. https://www.ncceast40.org I’m weird; for me, waiting for the next glaze test to come out of the kiln is like a kid trying to wait to unwrap a present. But while I’m waiting for the tests that will come out of the kiln on Thursday, I thought I’d make a post about the preliminary testing I’ve already done. Spoiler alert-I’m going to show you the best first, see above. To set this up, you have to realize that the clay at the East 40 is very rich with ingredients (probably iron, maybe manganese) that go very dark when fired to the high temperatures (roughly 2,380 degrees) we use for our glaze firings. I discovered a “magic powder” from my kitchen, that makes the East 40 clay fire light, and opens up striking color possibilities! I get eggs from a local farm, and if you’re familiar with truly free-range eggshells, you realize they are at least twice maybe three times as thick as factory farm eggshells. That's why eggshells build up fast at my house! Eggshells are on average 95% calcium carbonate, and calcium carbonate is one of the most common and useful ceramic ingredients. In glazes, calcium carbonate is usually sourced from whiting or talc. Eggshells, when fired, shrink in volume tremendously, which can cause problems in glazes. I did a preliminary bisque firing of my ground up eggshells, so that the shrinkage would happen BEFORE I put them in a glaze. You can see on the left in the line blend above, how dark the East 40 clay fires even though tis test was fired at a lower temperature than we use in the gas and wood kiln firings at the East 40. But wait! Add a little eggshell, (second from left square) and the color changes. Add a little more (center) and wow, a totally different glaze color, without adding any colorant!! But wait, there’s more. Add a little black copper oxide (colorant) and you get one green, a tiny bit more and you get a different green! I designed an entire 25 section biaxial tile-5 rows of squares by 5 rows of squares-investigating the interaction between 4 ingredients, as inspired by this line blend. All of the variations use the East 40 clay, and wood ash which is used as a flux (an ingredient to melt the clay into a shiny glaze). The balance of East 40 clay to wood ash is varied, explored both with and without the other two ingredients, the eggshells and the black copper oxide. Look for a post on when this tile comes out of the kiln! Like the tile above, this was the last row of a 25 section tile. Note that on the left, there is not enough wood ash to melt the clay enough to make a smooth and shiny glaze. Moving to the right, I'm adding a little more wood ash in each square. by tile 25 it loses the rocky texture of the first tile, getting closer to a usable glaze. Adding Wood Ash to East 40 Clay This test uses only two ingredients. Going left to right, I added increments of more wood ash to the East 40 clay. A few notes about this; for the ceramic artists out there, this was cone 6 oxidation. It's obvious that the 5 parts clay to one part ash is not nearly enough ash. (The ash is used as a flux, that is, to help melt the clay into a glaze.) I made impressions into each square with a finger, making a kind of "lake" within each square, and also applied the glaze unevenly to see how various thicknesses of the glaze would work. I'm working with such tiny amounts here that of course more testing is needed to nail down percentages, but it's pretty clear that the wood ash I was using, which was from the wood kiln at the East 40, needs to be over half the mix to melt the clay. I'm currently working on glazes for cone 10, so at that hotter temperature obviously everything will melt more than at this cone 6 (lower temperature) test. Adding a colorant I wish I had done the line blend of just the clay and wood ash first! Here there isn't enough wood ash in the mix to start, and as you add a colorant like copper carbonate, that tends to retard melting and make matters worse. Note that even .3 grams is way too much colorant for a first step! Instead of green, which we would expect from copper carbonate, we're almost at black. That's why I start with simple line blends-I'm not using much in materials to get this kind of information that points me in the directions I should go. Above, I used 4 g of East 40 clay to 2 parts of a commercially produced flux, the same percentage of clay to wood ash from the last test. The commercial flux has a stronger action but even so, it's under-melted. I'm using a commercial mason stain for the colorant. The main problem is that the clay when properly melted into a glaze is so inherently dark, it's hard to notice much color difference from the base glaze at left with no colorant. In the basic mix at left before I started adding rutile, it's melting ok but not great. Rutile can add color, texture and odd what I'll just call variations to the look of a glaze. Like the cobalt carbonate, it also makes the glaze more matte, or under-melted, under vitrified in ceramic terminology. Matte glazes are a thing, we don't always want super glossy glazes, but they can be more prone to leaching and other defects/weaknesses. I do want to do more tests with rutile going forward, just that every time I add an increment of rutile I know I need to add an increment of flux (melter) at the same time.
The way-back story I first used this clay when I was working on my master’s thesis, using a simple mix of half East 40 clay and half of a commercially available clay to make loom weights. (See crossing in my portfolio section) In my summer of 2022 Residency at the East 40, I used the clay, raw and roasted in a bonfire, as pigments for paints that I made and used in the “Imaginary Landscape” series of paintings that were featured in my Fall 2022 solo exhibition. During the residency, Walter Heath saw me grinding up rocks for pigments, and immediately had visions of using them to develop glazes. That summer I wasn’t ready to go there-but in 2023 I began preliminary testing, not just for the East 40 clay, but from local rocks I had picked up and processed. In this post I’m only showing the initial line blends I did with the East 40 clay, omitting all the rock glaze tests and tests on clay I dug out of my front yard-it’s a long enough post as is! |
Cindy VojnovicArtist & Educator Archives
January 2025
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