Oil pastel (also called wax oil crayon) is a painting and drawing medium with characteristics similar to pastels and wax crayons. They can be used directly in dry form; when done lightly. Oil pastels are considered a fast medium because they are easy to paint with and convenient to carry; for this reason they are often used for sketching, but can also be used for sustained works.
Because oil pastels never dry out completely, they need to be protected somehow, often by applying a special fixative to the painting or placing the painting in a sleeve and then inside a frame. The surface chosen for oil pastels can have a very dramatic effect on the final painting. Paper is a common surface but this medium can be used on other surfaces including wood, metal, hardboard, MDF, canvas and glass. Building up layers of color with the oil pastel, called layering, is a very common technique. Other techniques include under-painting and scraping down.