Different pastel techniques produce a variety of effects when using oil or soft pastels. The media are primarily built up in layers, rather than mixed like paint. Paper choice is important too, from its color to texture.
For lines and sketches, using the end of the stick or pencil is a basic method. Hard pastels and pencils can be sharpened to produce a more precise line. Turning soft and oil pastels on their sides or flat edges makes a broad swath of color. This is a good way to lay a foundation for building up layers of color that give depth to a picture.
Hatching and crosshatching are drawing and pastel techniques using parallel lines close together for blocking in a shape. Crosshatching adds more lines at right angles to the first, building up tone and shadow. More blending and layering will generally go over a blocked shape to fine-tune it. The lines are sometimes visible when a subject has been rendered by these pastel techniques.
Other artists prefer a well-blended look to a painting. The drier media lend themselves to pastel techniques designed to meld colors together. Paper stumps, blending sticks made of rolled paper called tortillons, or a finger are good tools for blurring colors. If fingers are used, they should be cleaned frequently to prevent unintended color mixing. Paper tools can be unrolled or peeled to provide a fresh surface.
Building in layers can be achieved by the previous pastel techniques as well as adding colors on top of each other and letting the eye blend them. Scumbling involves dragging the pastel stick across a layer of color that has been fixed, covering it with a rough texture through which the original can be seen. Another way to add texture is by feathering with fine, short strokes. These pastel techniques allow viewers to see the colors simultaneously and mix them together in their minds.
Oil pastels use all the same pastel techniques. Instead of a chalky binder, oil pastels have a wax and oil base. They can be layered with an impasto look, a technique where paint is put on in a thick, textured way that holds brush or knife strokes. Artists may incise oil pastels with a palette knife or pencil, removing layers of color to show others underneath. They can also dip oil pastels in turpentine or linseed oil, which makes them soft enough to spread around on the painting surface.
Paper is as much a part of pastel techniques as the media themselves. The best paper for pastels has some tooth, or rough texture, to it. Tinted paper eliminates the need for a wash, and different shades can accentuate different colors. Oil pastels can be used on many different surfaces, from paper to canvas.