The medium we call “pastel” is made by mixing pigments and binders together to form a vast assortment of coloring agents that come in soft, medium, and hard grades. They are available in a variety of sizes and shapes, including round and square sticks, chalks, pencils and pressed-powder block and pan forms.
Depending on the amount and quality of the pigment and binder, pastels differ dramatically from manufacturer to manufacturer, with the same also holding true for color.
When the mix of pigments and binders used to produce the pastel is low in moisture, it is referred to as a “dry” pastel. If mineral oil is used as the binder, it creates a waxy, crayon-like medium that never dries out and is called, unsurprisingly, an “oil” pastel. I work exclusively in dry pastel.
As for the history of pastels, it appears they were first produced around the turn of the 16th century and became a popular medium for painters about 300 years ago. Artists from a broad spectrum of styles, including Delacroix, Millet, Manet, Degas and Cassatt, created works in pastel, and, as anyone who attends a community art event today will know, it continues to be a popular medium into the present.
A good quality pastel is lightfast, meaning that it will not fade if subjected to prolonged direct sunlight (which, of course, should be avoided if possible). And when a lightfast pastel is applied to an acid-free, archival quality paper (or board), and framed professionally, it should last for centuries if not subjected to extreme variations in heat and humidity. Because pastels are simple mixes of pigment and binders, they are extremely stable and will not breakdown. You should remember, however, to have your framer keep an airspace between the painting and the glass, so the pastel will be protected from the smearing that might occur if the glass were laid directly onto the pastel surface.
I do not use fixatives (which adhere the pastel pigment to the paper) because they dull the painting by decreasing the luminosity and softness of the colors – qualities that add to the wonderful vibrancy of pastel paintings. Instead, I, as well as many other artists, use specialty papers and boards that act to trap the pastel and bind it to the substrate, without having to use color-flattening fixatives.
In summary, then, the art works that I create are made with high quality pastels and specialty archival paper/board and, when properly framed and cared for, should last many lifetimes.