Besides being easy to use, oil pastels are versatile, transportable and can produce some great results. But there are some things to think about before diving into your first oil pastel drawing.
Purchasing Oil Pastels
When purchasing oil pastels, it's always a good idea to understand the differences in brands and grades of available products, and more importantly, what factors go into some brands being more expensive than others. Like most painting and drawing tools, oils pastels are made of two components, a pigment (the color), and a salve (what the color is suspended in)--in this case oil and stearic acid. The less expensive, or student grade, pastels have much less pigment in them in relation to the amount of oils and acid. An oil pastel with more pigment in it will produce more vibrant colors, and a longer lasting final drawing.
Choosing a Surface
Unlike chalk pastels, the texture of the paper rarely shows through the layers of thick oil pastel once it is applied. For this reason, how much texture your paper has will be inconsequential. It is important to make sure that the paper you choose is sturdy enough (80 lb. or heavier) for the layers of heavy pastel, and that it is uncoated, to allow for the oil pastel to adhere.
Application
It becomes harder to apply layers of oil pastel over thicker applications, so its always a good idea to start with a thin application for your underpainting, applying thicker layers as you come closer to completing your drawing.
It's also a good idea to use the right size pastel for the job. Use larger pieces of pastel to cover larger areas, and smaller or "sharper" pieces for more detailed work.
Preserving Your Work
Since oil pastels never truly dry, the pastels will move around if handled too aggressively. Gravity will also eventually cause your painting to look like it is "drooping" once is hung. You can counteract this by using a spray fixative with holds the pigments in place indefinitely. Oil pastels with high amounts of stearic acid in them will eventually eat away at the paper. Using higher quality pastels will prevent this.
Special Techniques
One great technique exclusive to oil pastels is the fat that the drawings you create with them are still malleable after application. You can use a brush dipped in a small amount of oil or painting medium to change the shapes in our work. You can also use this technique to blend oil pastels, creating seamless gradations in value.
