> My HS ceramics class recently did a project based on Bernard Palissy's rustic platters. The students rolled out slabs of clay and then laid them in platters (picked up from the thrift store) to give them form. One student did a beautiful ocean scene on her platter. She used red clay for the actual platter and then added pieces cut out of white clay on top. The problem is, as the platter dried, the red clay started to crack. I originally told her to mend it with some soft clay. The platter cracked again. The next time we mended it with a vinegar slip. The platter continued to crack. The red clay we have does tend to be a bit more difficult to work with in general. Is there any way to save the platter at this point? Right now it's in a leatherhard state. Any advice on this matter would be greatly appreciated.
This is why I am such an enthusiastic proponent of using clay as an art medium. Working with clay is an ideal way to learn how to learn. It forces us to experiment. Experimentation works. There is always a logical reason for all the stuff that unexpectedly happens. We discover the reasons, and any thinking student can do it. Practice and experimentation quickly pays off and makes things get easier and better. In this case if we ask the student why this happened, she could probably guess that clay shrinkage is the culprit and uneven air drying is probably the cause.
Starting over is always an option if your student has figured out an idea about why the problem occurred, and a theory on what could prevent the problem. What if we encourage students to invent solutions and experiment to see what works?
What if we ask the students to propose their own creative salvage ideas? Could we encourage the student to invent salvage options to consider and try? I try to reassure them that learning how to think and how to invent is vastly more valuable than any one art product.
What follows are some things I have learned by experience, but I would not automatically tell these things to my students. I have actually enjoyed learning them by experimentation and experience. It would not have been nearly as interesting for a teacher to have told them to me.
As a salvage solution, I would guess that your student could fire the pieces and make it into an assembled tile piece using the old thrift store plate as the support for an assembled mosaic wall piece. This of course was not the plan. Art often changes as we produce it. By adding additional breaks and using good judgement on grout color, it might be better than the original idea (or worse). Art is first a search and a learning process. This sometimes results in leftover products that have a bit of value. The main thing is to learn from the experience and take note of what is learned. What if the students journal these experiences and make sketches for the next great project? I often find that sketching solutions to problems and mistakes really brings new ideas to mind.
Flat clay pieces present unique drying and shrinking challenges. Sometimes I intentionally thicken the edge a bit to slow the edge shrinkage. I have found that adding from 3 to 20 percent silica sand or grog to the clay cuts down on shrinkage. Adding fiber to clay is often helpful. Experiment. I turn plates over as soon as possible so the center gets the same air as the edges. Otherwise the raised edges get air on both surfaces (inside and outside) and the center only gets air from the top side. Another precaution is the spray water on the edges before the edges shrink, or wrap the edges with plastic to slow the edge shrinkage. Sometimes I dry flat work on wire racks that have lots of air space under them. Wax emulsion can also be used to slow the edge drying, but it may leave a line along its edge because the the evaporation draws solubles to the surface next to the wax. These often show after glaze firing.