Although often considered a child's toy, modeling clay has been used for thousands of years to create everything from pots and plates to sculptures and animation figures. Modeling clay can be made of a variety of materials, even the flour and cornstarch in your kitchen cupboard.
Natural Clay
Clay exists in nature. It forms when granite breaks down into fine sediment, particles of rock that have been worn away by wind or water and carried elsewhere to be deposited at the bottoms of lakes or rivers (these are known as secondary clays). The particles are very small---less than 1/256th of an inch---flat, and hexagonal. The shape of the particles causes the clay to be slippery and malleable. Common types of clay include kaolin and bentonite.
There's evidence of clay being used to make pottery in Japan about 10,000 years ago.
Modeling clay is a manufactured product that shares some features with natural clay, but can be used again and again and, depending on the type, not dry out.
Oil-Based Formulas
In the late 1800s, two men---one German and one English---developed oil-based modeling clay that remained pliable. This never-drying clay is known as Plastillin®, developed by Franz Kolb in 1880, or Plasticine®, the trademark given to the clay developed by Englishman William Harbutt in 1897, or as Plastalina®.
Oil-based clay can be molded and shaped by hand or with tools. It warms and becomes easier to handle as you work it with your hands. But its softness makes it difficult to hold fine detail well. When modeling is complete, oil-based modeling clay will retain its shape and not dry out.
Oil-based modeling clay is frequently used in a type of animation called claymation. The characters (and, sometimes, the settings) are modeled out of this clay and then photographed using stop-motion photography. Perhaps the most well-known characters in claymation are Nick Park's Wallace and Gromit.
Polymer-Based Formulas
Another type of modeling clay is a polymer-based clay, sold under the brand names Sculpey®, Premo Sculpey®, and Fimo®.
Unlike oil-based modeling clay, polymer-based clay can be hardened by drying it in an oven. After drying, it remains somewhat flexible. Dried pieces can be painted with acrylic paint, if desired, but because the clay is available in such a variety of colors (including metallic, glitter and translucent) painting may not be necessary.
Polymer-based modeling clay can be used in jewelrymaking, vases and decorative pieces.
Unused material should be kept in a sealed container to prevent it from drying out.
Dough-Type Formulas
Modeling dough tends to be softer and easier to work with than either oil-based or polymer clay, so it is a better choice for use by young children. It is usually a mixture of water, salt and flour along with pigments that create vivid colors.
Modeling dough will dry over time if left exposed to air, although it may crack.
Probably the most familiar brand of modeling dough is Play-Doh®, which started more than half a century ago as a wallpaper cleaner. When the cleaner's inventor, Joe McVicker, heard a teacher complain that the clay she had was too difficult for her students to use, he sent along a can of his pliable, off-white compound. In 1956, Play-Doh was introduced as a toy, and since then has sold more than 900 million pounds.
Make Your Own
Many simple recipes for making modeling clay are available. Here's one.
Ingredients:
2 cup salt
1 cup corn starch
2/3 cup water
1/2 cup cold water
In a saucepan, combine 2/3 cup water and salt. Stir over heat for 4 minutes. Remove from heat; add cornstarch and 1/2 cup cold water. Stir until smooth and then return to heat until the mixture thickens. Remove from heat again and allow to cool thoroughly.
