Here are some pictures that I took during the opening weekend at The Kimbell, October 5th and 6th, 2012.
After almost exactly two years of working on this project, I shipped three large pots to Ft Worth last week. These pots are for a site specific installation in the courtyard of the Kimbell, and will be up from October 5th to December 30th, in conjunction with the show: The Kimbell at 40 an evolving masterpiece.
The pots really embody the challenges of the materials.
This is the text that will be on the wall near the pots.
Adam Silverman: Reverse Archaeology, The Kimbell Pots. 2010-2012
This site specific installation was made entirely from materials gathered from the Kimbell museum site (Several different clays from the ground, Water from the KImbell fountains, wood ash from trees, cedar shavings, acorns, iron from rust, concrete and travertine). The project is intended as an offering to the Kimbell, this courtyard, and to Louis Kahn and Renzo Piano, by making objects that honor the materials harvested from the site. By combining the use of geometry in form making, with the very primitive technical capabilities of the materials, the resulting vessels feel as if they came from, and belong to, this location (Ft. Worth and The Kimbell).
After two years of working with these materials, I have edited things down to a small collection and combination of viable materials for making pots. When the pots get big, as big as I need them to be for the installation at the Kimbell, they can’t even handle cone 02 (about 2,000 degrees f ). The stress of the heat caused a lot of cracking in the test pots. My assistant Roger Lee threw this big pot, it was fired to cone 02. You can see the cracks. So we took the temp lower, to about 1,900 degrees max, which makes a difference in the strength of the clay. The problem at those temperatures is that many of the materials that would give us interesting glaze effects, like wood ash, or glass from the site, won’t melt at such low temperatures. The glaze on this pot contains Borax, a material that is not from the site, which is why the glaze is nice and glassy. Although it is tempting to use materials from off site that would give us more controllable and beautiful results, I ultimately concluded to stay 100% true to the original concept and use only materials from the site for the clay body and any slips or glazes that we would make and use.
As the deadline to finish the three large pots for the Kimbell’s 40th approaches, we have ramped up the pace of activity on the project, moving it from simmer on a back burner to boil on a front burner.
Since the last post in May, we have set aside clay #3 as it has proven too unreliable. So at this point we are focusing on clay #5 and working on scaling up the test pots, and developing glazes at the same time.
The clay fails and melts at cone 5 and above, so we are operating at cone 02 for now. Here are some glaze tests using different ingredients from the site. In the glazes we are using three different clays (#1, #6, #7) each of which I have only a very small amount, so they are appropriate as glaze ingredients, not as clay bodies. One is white, one very black and one very red, so the results are varied and interesting.
I will probably use there different glazes, one per pot, to further articulate each piece, beyond just their forms.
Here we are making some more wood ash from Kimbell trees for the glaze tests. Below are glaze test batches and then test tiles and some results. There are some promising glazes coming out.
I have been struggling to figure what the white spots are that surface in the pots after they come out of the fire. If the pots are just low fired, to bisque temperatures, or in other words, not vitrified, then the white spots usually do not surface, and the pots are fine. But I have been trying to reach high fired temperatures, so that the clay is vitrified. And with several of the individual clay bodies, as well as the blended body that I had high hopes for, the spots start to surface after a day or so out of the kiln, and eventually lead to the pot decomposing…literally falling apart over time.
So I made an appointment to meet with John Pacini, the clay manager at Laguna Clay. John knows more about clay than anybody I know. John Brooks, the owner of Laguna also joined the conversation.
John P. immediately identified the culprit as gypsum, or some other, similar form of calcium. He explained why the pots could sit unfired for a year and not have the calcium surface, but that once they were fired, the calcium appeared, up to a week after firing, and would eventually undermine the structural integrity of the pot, causing it to slowly turn to a pile of rubble.
Apparently, if the pot is unfired, or fired low enough, the gypsum can get all of the moisture that it needs from / through the clay. But once the clay is high fired, and has no moisture at all in it, the gypsum, in an attempt to rehydrate itself, migrates toward the surface of the pot in search of moisture. As it moves through the clay, it destroys its molecular and structural integrity, and the pot eventually falls apart. Which is so bizarre and fascinating and amazing to me. John suggested as a first course of action to re-seive the clay through a finer, 100 mesh, screen. It had previously been screened down to about 30 mesh. His thought was that the 100 mesh screen would catch most of the gypsum, and that if any gypsum remained behind, and if it fit through a 100 mesh screen, it might not cause any problems to the clay. Since getting this advice, we have re-screened the already blended clay body of clays 2,3,5. And we screened a batch of each of the three clays, 2, 3 and 5 individually as well. The blended body still shows signs of the gypsum when fired to cone 5. Clay 3 and 5 on their own are gypsum free now, and clay #2 seems to be the one with the serious gypsum problem, and the one that is contaminating the blended body. So for now, I will focus my energy on using clays 3 and 5, while continuing to try to fix clay #2.
The clay body that I am working with now, equal parts clays, 2, 3 and 5, has two main problems. One is the continuing problem of post firing decomposing of the pots (which I’ll deal with on the next post) and the second is the clay being “short” or not very plastic, which means that it doesn’t like to be thrown very large at all. It tends to shear or tear when I am throwing it. I could add some good ball clay to the mix to improve the clay quality, but I am trying to use only materials from the Kimbell, so adding outside clays is not an option at this point. The first project I have with this material is to make three large pots for the Kimbell to celebrate the 40th anniversary of the original Louis Kahn building, which is this October.
So here I am trying a technique that I saw executed online by the North Carolina potter Daniel Johnston. He learned it working in Thailand, where the clay had similar limitations as the clay I have from The Kimbell. He rolls out small coils, like hot dogs, then wheel throws a base to the pot, and slowly works each small coil onto the base, bringing the walls up as he goes, and then throwing the assembled coils, and adding coils, and throwing it some more to keep it centered and to make the walls more consistent and shaped. I made one big, and very bad, pot, about 24″ tall I think, using this technique. It looks like Fred Flintstone made it. But it did work. The pot was very solid and very strong. I decided not to fire it since it would decompose later anyway, hence wasting a lot of clay, so we threw it back into a bucket of water to turn it back into usable clay. Even though it hadn’t been fired, it was very strong and had to be broken up with a large hammer. With practice I think this technique may work for this project.
The last pictures in this post show Jackson Foster, my new intern for this project. Jackson is taking a year off between high school and starting at RISD this fall, and he is spending two months helping me in the studio, mostly with the Kimbell project. You can see him carrying and destroying the big pot I talk about above.
I have split some logs of each of the three woods I have from the site (Cedar, Elm and Oak) and taken them home to burn in our file place. Then cleaned the ash and am now testing it on its own as a “slip”.
These first pictures are using just cedar ash and water mixed into a thick slurry and brushed onto leather hard pots, in one case over another clay slip and with dry ash just sprinkled onto the pot (pot k3.12). The results are interesting, but not what I had hoped for at all. Cone 5 is not hot enough to melt the ash on its own, but in some cases the pots melted anyway. Or the ash is dry and unmelted, and not textural enough to be interesting as it is. Next I’ll try the ash on bisqued pots, and also try firing this clay to cone 6, and then try the ash mixed with clay to lower the melting temperature.