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   Working Big: Sculpting Industrial Clay Pipe
 

   In June of 2004 I had a wonderful opportunity to work at the Mission Clay pipe factory in Pittsburgh, Kansas. I spent 12 days working inside the plant, carving 12 terracotta sewer pipes, with expert help from the factory workers. These pipes are termed "the largest pipe in the world". All the pipes have now been fired, without any structural problems, bringing the project to successful completion.                                                                
  Work began on Monday, June 14th. It was amazing to see the team at work extruding ("pressing") the huge pipes, which actually steam from the intense pressures of the hydraulic machinery. Two 8-ft pipes and two 12-ft pipes were extruded and delivered by forklift to the designated studio in dryer A1. (Fig.1) A square flue-type pipe, 4 x 4 feet, had been saved in shrink-wrap from the previous week. Two days later, I got another two twelve-foot and two ten-foot pipes before production switched to smaller pipes. Because of production schedules, the work period was tightly scheduled from June 14 - 26th.

   Previous experience carving raw industrial pipe at the Gladding, McBean factory in Lincoln, California had taught me to expect a very coarse, gritty clay body. The clay texture changes from sand-in-butter to a dry concrete texture in only eight hours, if left uncovered. It is essential to move rapidly around the pipe, marking the designs, carving the images, and painting areas of color with slips 
   I use a needle tool to draw directly on the pipe. When extruded, industrial pipe has a smooth, polished skin, which shows any mark dramatically. Next I use a small trimming tool to cut a groove along the outline. The small end of a pear-corer enlarges this groove, at which point the tool is flipped and the outline again carved out. Now the smooth clay of the outlined image is marked out in a wide, shallow groove. It is important that the transition between the deeply carved areas be as smooth as possible.

   Preliminary sketches for the pipes are important when plotting out the sheer scale of a twelve-foot pipe. Designing for a narrow, vertical image led me to consider swimmers, tornados and circus scenes, in order to logically stack the figures above one another on the surface of the pipes. Fig.2  Artist w paper mural, "Primavera".
   For a large image like the trapeze artist in Circus, I needed to carve deeply around the arms and face. (Fig.2) This presents a special problem, since the clay body used for industrial pipe contains a huge proportion of refractory material, and the pieces range from sand to lumps the size of small marbles. Inevitably these do seem to appear right at the point of fine detail, like an eye or lip.  Fig 3. Detail of face of acrobat, Circus II.

   I found two solutions for the detailed areas of carving and modeling. One is to add softened clay trimmings to deeply pitted areas. Such areas need to be quite small, however, because of the risk that the added clay will not adhere through the firing. This led me to a new approach. After outlining and preliminary carving, I used a toothed rib, scratching up the surface vigorously, bringing up the finer clay particles. This is followed with a rubber rib, compressing and refining the surface, which reacquires its highly polished, almost burnished look. The rubber rib has to be used with considerable pressure for this to work well. Sliding the edge of the rubber rib along the grooved outline makes a single deep line around the contour of the image, helping create the illusion of depth.

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Color and Design
   I used slips formulated at Leslie Ceramics, generously donated by John Toki. Four months of testing preceded the project, to check the fit, and making it possible to choose colors which worked well with the fired terracotta of the pipes For the pair of pipes titled Circus, Circus, I used a bright vivid blue that evokes a festival feeling and suggests sky or a big top tent around the acrobats. I had to make a 30-inch brush handle to reach the bells of the tall pipes, even from a scaffold, but had no problems with dripping. Twister (Fig. 4 Twister: cat napping on chair) is intended to be a colorful melee of forms flying through the air. The images are outlined and carved in shallow relief, with the exposed pipe texture left for contrast
   I looked at the effects of different tools, textures and brush sizes. Because of the generous amount of underglazes provided, I wanted to use them to maximum advantage. I found alla prima (wet-on-wet) painting to be a wonderful way to create depth in landscape. This expressive method makes it possible to blend the slips on the clay surface, giving a convincing sense of depth and motion to the sky. It is a pleasure to work a large area so vigorously. The technique appears on Dos Rios and Splash.

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                                                                                       Figs. 5, 6, 7, 8
   Dos Rios, a pair of 10-ft pipes, shows life by the river in both Kansas and California. The pipes are intended to form a single piece. It is important that the contrasting landscapes form a unified image when viewed together, so I used string and pins to ensure matching horizon lines, and a three-pronged garden tool to make matching water lines on the front face of the pipes. I spent particular care on the human details of the images; (Fig.4) the scale of the pipes makes this especially important. (Fig.5)
   Splash is not carved or painted at the top, leaving the skin of the clay untouched. (Fig.6) A 10-ft diver, a child in a swimming tube, and a third figure, cannonball diving into the water and holding her nose, comprise the images. Carved waves in an Art Deco style surround each figure, with bubbles floating above them as they splash into the water. This pipe also refers to Kansas clay artist Waylande Gregory, whose work Fountains of the Atom appeared at the 1939 World's Fair.

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The Factory Setting 
   Walking through a working factory means being constantly alert for forklifts with pallets of pipe, as well as other vehicles and busy production areas. The large pipes are so big that human comparison can be quite startling. (Fig 10. Moving the new pipe).

   The safety equipment required for the factory includes hardhat, steel-toed boots and jeans, all of which make working in the hot, wet environment unique. I was careful to drink water all day long. During the hot midday, I drank electrolyte solutions to prevent muscle cramps.

   The work site space was about a thousand square feet, in "dryer" A1. The dryer setting is where the industrial pipe is placed after being extruded. It is designed to be very wet. There is a sub floor fifteen feet below the pipe, which can be seen through the welded steel grate of the floor. This floor seems treacherous until you have seen a forklift with a 4000-pound pipe driving across it, then any fears of dropping through it vanish. .

   The sub floor is necessary to maintain the humidity. We hosed it down through the grate, four or more times daily. We were also supplied with a special gauge to monitor humidity and temperature, which should be within 10 degrees of each other at all times

  The factory workers are extremely knowledgeable about the pipe conditions. We received daily visits in dryer A1 to check progress, offer help and encouragement, and enjoyed several visits with family. It was recommended that the pipes be wrapped for even drying, using 10 x 25-ft rolls of 2 ml plastic. There was discussion about needing a very slow (28-day) firing schedule after the important, month-long preliminary drying period. A further consideration was the rapid cooling of the kilns, which is inevitable after summer's end. In order to protect the pipes, they were carefully loaded by forklift into the center of the enormous beehive kiln, insulated by the surrounding pipes. All these and many other skilled solutions made possible the successful collaboration of the Mission Clay pipe project.

Susannah Israel
Oakland, California