To avoid dead, unharmonious passages in our paintings, we were encouraged to avoid pure white and black as pigment choices.There are times, though, when white and black can be useful. Just as a wet-medium painter has to rely on white to lighten certain pigments to achieve a lighter value (tint) and black pigments are often employed to darken a pigment (shade) so too must the dry-medium pastelist. In fact most of our pastel sticks have some degree of these added already in order to achieve the value ranges we use. Used wisely, a pure white and black stick of pastel can produce an expanded value range within our work. Since pastel isn’t as easy to mix together as wet media, we have to layer to achieve a mixed, or fused, effect. This is where softer pastels will work better. Harder pastel sticks tend to push the pastel around, even scraping the under-layer of pastel, and depositing a minimal amount of pigment. A softer pastel stick will allow for a generous amount of pigment to be deposited, fusing with the previous layer of pastel and producing a mixed appearance. For example, say the bottom of a sky area needs to be lighter, and you have used the lightest blue pastel you have. By lightly pushing a little pure white pastel into the area and not over rubbing but allowing the pigments to fuse, you’ll be able to represent the value needed. Conversely, placing black pastel into a dark color until the desired value is achieved can darken an area (See my example above, in which white has been added to the blue and black has been added to violet to alter the colors’ values).
So, white and black can be useful for the pastelist and should not be overlooked when setting up a working palette. It seems that sometime we can benefit from a little “black and white” ideology!