The white filler is responsible for the delicacy of hue associated with light colors such as flesh tints. Darker fillers create rich earth tones and deeper hues of colors. They can be worked and blended into thick, velvety finishes, covering large areas very quickly. As a result, however, soft pastels disappear rapidly. They are also some of the most expensive and fragile pastels.
Oil pastels are raw pigments combined with oil binders instead of gum.
They produce thick, buttery strokes, and their colors are deeper and more luminous, like oil paints. They are also less crumbly and smearing. Oil pastels are suited to direct, spontaneous work, and can be diluted with turpentine or mineral spirits. Choosing your Colors While most paints can be mixed from a relatively limited palette to form many different colors, pastels require a large number of separate sticks to achieve an adequate range of hues and tints. Every pastel company has a full collection of pure, full-strength colors.