If you’re a little unclear on the difference between oil paints, pastels, charcoal, and graphite, you are not alone. Let me explain just a little about each so that you can choose which medium suits your needs best. First, two of these mediums are black and white: charcoal and graphite. Pastels and oils use color (pigments mixed with a little binder).
Charcoal comes in black sticks of various softness, which are used both from the small, pointed end or used flat in wide strokes. There are also charcoal pencils for finer drawing. It allows the full range of shades of gray and may be applied to white, off-white or gray papers and boards. Charcoal drawings are sometimes highlighted with white chalk, if they are done on gray papers. All charcoal drawings need to be framed under glass because they are smearable (although fixative spray helps) and because paper cannot be cleaned easily.
Graphite is what we think of as an ordinary pencil, but since there are other types of pencils, this is the specific terminology. Artists have a range of hardness/softness from which to choose. Like charcoal, it can be a very light, delicate drawing or have surprisingly dark and forceful strokes, but there is almost no end to the detail that can be put into a graphite “pencil” drawing. When you need fine detail or a smaller picture, this may be better than charcoal. Pencil drawings should be framed under glass because they are smearable (although fixative helps) and because paper cannot be cleaned easily.
Oil paint is the king of all media. Its pigments are mixed with oil, usually linseed oil, and it can last centuries. The colors can be brilliant and mixed almost infinitely. It does not need to be framed under glass because the nature of the medium, when dry, makes it unsmearable and relatively easy to clean. The colors are rather expensive. Although it is quite durable, it is subject to yellowing and cracking after many years.
Pastel is possibly the most misunderstood art medium. It should not be confused with chalk. Chalk is a cheap, limestone substance impregnated with dyes, whereas pastel is pure pigment, the same pigment used in making all fine art paints - including oils - and relatively expensive. Because it has no liquid binder that may cause other media to darken, fade, yellow, crack or peel with time, pastel is one of the most permanent of all color media when applied to an acid-free ground and properly framed. Pastels from the 16th century exist today as fresh as the day they were painted – no restoration needed, ever!
Pastels do need to be framed under glass to prevent smearing and soiling. It is important to separate the surface of the artwork from the glass, either by framing with double or triple matting, or using a linen liner or an invisible spacer to keep it from the glass. I always include framing instructions when I ship pastel paintings (which can only be shipped unframed). IMPORTANT NOTE: Never use plastic over a pastel, as static fields build up and attract the pigment off the surface of the art!