The tone of the surface you choose to work on has a profound effect on the appearance of the applied pastel (see my January 19 blog post for more about that). Since most of our subjects are made up of diverse value and color relationships, choosing just one tone on which to work can be a challenge. Due to this, many pastelists have relied on various techniques of underpainting as a means of setting-up an understructure in advance of pastel application. Ever the inventive group, pastelists have experimented with a wide variety of methods and products for these underpaintings. This has opened pastel up to a variety of mixed-media techniques with the use of watercolor, gouache, acrylic, liquid pure pigments, acrylic and even highly thinned oil paints.
A different medium does not have to be a prerequisite for pastel underpainting, though. Pastel itself is quite capable of producing a variety of beautiful effects. A common method is to lightly apply the desired pastel and then rub or smear it around the surface with the use of a rag or strong paper towel. Overuse of your hands should be avoided for health concerns, and be careful of generating pastel dust during this process; the biggest concern pastelists have is airborne pigment inhalation.
If a painterly look is desired, pastel can be wetted with water, paint thinner, gum turpentine or rubbing alcohol. Making pastel wet produces interesting effects as it drips and runs around the surface. The pigment pools and happy accidents occur. Remember that when pigment is wetted, it will appear brighter and darker. Once it dries, it will return to its original state. As exciting as these happenings can be, there are surface issues to be considered. Water on a highly rag surface or lightweight paper can produce wrinkles. If you plan to use water, it is best to have the paper mounted in advance of painting (see previous posts about mounting here and here). Rubbing alcohol can soften certain pastel surfaces that use an acrylic binder. Paint thinner and gum turpentine can have adverse effects on the appearance of certain pigments. Test for these in advance of painting by experimenting on a scrap of your preferred surface and mixing the solvents with the pastels you will be using. As long as the surface can tolerate the product being utilized and good archival techniques are employed, there is nothing to fear. Experiment, have fun, and enjoy the creative possibilities!
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