2010 - part 2
As usual, last winter in Texas I developed several concepts which I brought back east. I had been thinking for many years about a structure that through its lower undulation suggested the weight of its upper part. I eventually came up with a form that, at least to me, has a female and African mask/figure-like quality. It is both dynamic and stately. (photo 1) I debated long and hard about the appropriate material, and relishing challenges, decided on concrete. To quote John Lauter the ultimate US concrete architectural innovator: "Concrete is the very best material for withstanding sun, wind, fire, and time" To contain the considerable weight, which I estimated would be 27,000 pounds I could only imagine using steel plate to construct the form. As we started to build the form we ran into problems. With all the curves, sloping sides and top of the design, establishing dimensional references and relationships had us scratching our heads big time. We first cut ribs to match the arcs of the front and back surfaces and then pressed the ¼" surface plates to the ribs. Before long we discovered that we were trying to defy the sculpture's inherent geometry. I had wanted the narrow sides to have straight edges as in the model while the front and back surfaces maintained a consistent radius. I discovered that these two requirements could not co-exist, for the front and backs are really conic sections. If you to project a straight line on the surface of a cone, you get a curve. Well, knowing me, you know I could not live with curved edges on the narrow sides as they weaken the bold upright power of the piece. Once again, as we saw last summer, slight inaccuracies in the model did not become evident until we started working on a large scale. We wound up cutting some of the ribs away so that we could cheat the front and back curves ever so slightly until we got the edges straight. All this proved much more difficult because we were making outside forms which had to be self supporting. If we were, instead, making a steel sculpture, we could have braced one side against the other. This image (photo 2) shows the inside surface of the front side. The outside of the back is standing to the right. In order to keep the upper part of the structure "light" I decided to develop a 6" thick shell of concrete by creating a foam infill. (photo 3) The forming of this did not go quite as I had hoped because the liquid urethane mix did not flow out much before it started to expand. But we did get it done, and secured in place so that it would not float out of the concrete. In order to be able to stand up and lift the structure, we developed a thickened/reinforced area at the top with two stainless lifting nuts which will receive large, removable eye bolts. (photo 4) You'll also notice from these images that each re-bar frame was curved front and back and had a different dimension. We built many bending jigs and formed the re-bar laboriously by hand to accomplish this. Before going further, we made a form (photo 5) for the base and poured it so that its rebar could be tied into the upper structure. Once all the fabrication of the form components was complete, we moved them outside to be sandblasted, then, back in to be painted and coated with a form release. We then bolted the whole assembly together and gingerly moved it out for the pour. Because the form was sloped along the top and higher than the chute of the concrete delivery truck, we dug a hole to bury the tall end and level the top. (photo 6) While we had been marching along with the fabrication, I had been consulting with various concrete companies to gain their advice on the mixture. The problem being that we needed a very high strength mix that would flow down around all the curves, foam infill, and re-bars. The curves and tightness of the spaces precluded using the common poker-style vibrator. It was determined that we should use various "self consolidating" admixtures with lots of cement and smaller aggregate. These would allow the concrete to flow out without adding more water which would weaken the mix. I also wanted integral color so that had to be added as well. The supplier sent their quality control guy to create the right mix and retain samples. (photo 7) Knowing that neither Brian nor I were especially skilled in finishing the top surface and wanting it to as closely match the finish of those surfaces up against the form, I hired a local concrete finisher. After a week of unfavorable weather, we got a break, and away we went. (photo 8) We decided to fill from the center point only, but disturbingly it appeared that the aggregate was separating from the cement more on the far side of the chute's end. Also,(photo 9) we discovered that the material proved to be very difficult to hand finish smoothly as the small aggregate kept dragging out. I feared that we had not gotten the pour I imagined, but we would now have to wait until we stripped the form to know for sure. A couple of days later, my fears were confirmed. Fortunately the lower section which will see more severe stress came out quite well, but the upper section did not. We now had to wait several weeks for the concrete to strengthen before we could lift the whole structure out of the hole. I scrambled for solutions to: "what do we do now?" (photo 10) More consultations and more research led me to several conclusions. First, though all my past works have been one-of-a kind, I may wind up considering this pour as the "artist's proof" (in the explorative spirit of print making). Second, we should roughen the existing surface and use a bonding agent and a surface filler to re-smooth the surface. Unfortunately, doing so will trash the chosen color. Once all that happens (and now we're talking next spring) a whole new, as yet to be determined, surface should be over-sprayed. (photo 11) We were going to move the piece out to the meadows and set it up on a foundation which we had been preparing. In this way we could test it structurally through the winter months, but heavy autumn rains rendered the fields too soft to move it. |
In this new section, "Letters to Jules", I share my thoughts through discussion and evaluation of my artistic endeavors each fabrication season. I hope these words and images give you further insight into my working process and concerns. Typically, I spend from late May through October at my VT studio where I fabricate large scale works with the help of assistants. From November to May in Austin TX, I explore different materials, write proposals and develop concepts and models for future pieces. I welcome your input, comments, and communications. My letters to Jules...
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