Notebook, 1993-



Plaster of Paris. A fine white or pinkish powder, made by the calcination or dehydration of gypsum (see alabaster), which when mixed with water forms a quick-setting paste that dries to form a uniform, solid, and inert mass. It is used in sculpture for making moulds and casts. [Oxford Dictionary Of Art. Chilvers, Ian, Harold Osborne, and Dennis Farr, eds. Oxford, New York: Oxford University Press, 1988.]

Plaster Plaques or Reliefs. Plaster plaques or reliefs are very easily created in the upper elementary grades and junior high school. Each child can bring a small box in which to make his plaque. Plasticene (or earth clay) is patted or rolled flat, and the entire bottom of the box is covered with a layer about a half inch thick, on the surface of which the children can work their ideas out directly. They can make many exquisite shapes and textures by pressing a variety of objects into the soft clay. Dowel rods, buttons, natural materials, spool ends, large nailheads, keys, wire screening, and twigs are only a few of the possibilities. If the child's first idea doesn't work out satisfactorily, he can smooth the surface out again for a new start.

The teacher may wish to have the children work out their ideas first on paper with chalks or crayons. The teacher can explain the steps that follow more easily to children if he has prepared a sample for illustrative purposes and perhaps has a finished plaque from another class or even one that he has made himself.

The children begin by digging directly into the plasticene, using tools fashioned from tongue depressors split lengthwise. Into the plasticene they carve, deep in some spots, shallow in others, until they have expressed their ideas as fully and originally as possible in this material. The plasticene can then be given a very thin coat of petroleum jelly; however, this is not absolutely necessary, as there is already oil in the plasticene mixture. It does, however, prevent bits of plaster from adhering to the plasticene.

The next step involves the mixing of plaster of paris in a container, such as a plastic washbasin or mixing bowl, or a #10 tin can. The plaster is poured onto the plasticene carving to a thickness of 1/2" to 3/4" . While the plaster is still wet, the child can insert a loop of soft wire near the top of the back in order to hang the plaque. If the teacher encourages the children to jostle the boxes slightly without lifting them from the table while the plaster is still liquid, any air bubbles that might have been trapped in the plaster will rise, insuring a more uniform quality.

After the plaques have dried overnight, the boxes can be torn away and the plaques lifted away from the plasticene molds. Slight imperfections can be carefully carved away with an ordinary paring knife or smoothed with a small bit of sandpaper. After the plaques have dried for several days, they can be given a very light sanding to remove all traces of the petroleum jelly, which might offer some resistance on future painting operations. Now the plaques are ready for painting. Ordinary water paints, tempera paints, enamels, or oil-based paints are satisfactory for finishing this project.

If ordinary earth clay is readily available, it can be used just as effectively as plasticene. Unlike plasticene, which can be used over several work sessions, the earth clay should be carved and the plaster poured while it is still malleable. When the plaster has hardened sufficiently to pull it free from the clay, it may be necessary to take a moistened brush to wash away clay particles that still adhere to the plaster.

The teacher will find the children very excited about this project and wanting to do it another time.

[Meaning in Crafts. 3rd Ed. Mattil, Edward L. Englewood Cliffs, New Jersey: Prentice-Hall, 1971.]

Plaster Printing. A print produced from an intaglio plate that has been converted to a relief print by making a plaster cast of it, thereby causing lines that were originally incised to stand out above the surface. [Oxford Dictionary Of Art. Chilvers, Ian, Harold Osborne, and Dennis Farr, eds. Oxford, New York: Oxford University Press, 1988.]



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