First I lay in an “under-painting” using a little paint mixed with a lot of solvent to make a “wash”. A wash using solvent dries fast and is transparent enough that I can still see my sketch underneath it. I cover the entire board with it. Since the background is a sun-lit field, I choose yellow ocher. This establishes the unifying color so that colors added later can be adjusted to it properly without the painting looking choppy. Other colors will be added (first in a loose wash) to establish basic shadow areas such as the forest. As more detail is sketched in, paint will be added a little thicker to these objects, either at the consistency in the tube or “bled” (by using an uncoated paper plate as a palette which leeches some of the Lindseed oil out of the paint). Lindseed oil gives the paint a rich luster, but it dries very slowly. Working “wet-into-wet” makes paint easier to blend and can give some wonderful effects, but makes detail work nearly impossible. Also oil-saturated paint increases the potential for unwanted smudges on the painting and oneself. Therefore, I reserve Lindseed oil for the later stages or I let the painting dry, then go over it with Damar Varnish or some other shiny medium.
Stretched canvas with a coat of gesso on it (to eliminate absorbency) is the traditional surface for oil paintings, but it is not necessary. Masonite boards with several coats of gesso are good. Paint a thin coat of gesso on the masonite. Let it dry. Sand it lightly to remover irregularities. Apply the next coat of gesso, etc. I have also used illustration board. Hot press illustration board is smooth and less absorbent; cold press is textured and more absorbent. Absorbency of the board will bleed the oil, of course, so decide the method and effect you want before choosing the surface. I am using foam core board this time. I knew it would work and I had several 30″x40″ pieces of it in stock. However, if foam core bends too much, it will break and if the edge is hit too hard will be damaged. This is a drawback. Use caution.
There are many shapes and sizes of brushes used for heavy-bodied paints such as oils and acylics. Some are of natural fibers some are of artificial fibers. Most have longer handles than do water color brushes. Some examples of these are Flats (long bristled, squared at the tip), Brights (shorter bristled, squared at the tip), Filberts (long bristled, tapered slightly at the tip), Rounds (large bellied, but tapered to a point at the tip), Egberts (long bristled, but not tapered much at the tip), Fans (flare out like a fan), etc. Good brushes are worth the price, but should be properly cared for. Clean each thoroughly with solvent after each use. At the end of a day’s painting session, it is also good to wash them with warm soapy water, re-shape if necessary and let dry before next day’s painting session. Never let paint dry in them and never put them in the pot with the bristles down.
Solvents for oils include Turpentine, Turpenoid, and Webber Turpenoid Natural. I have used all of these, but prefer Webber Tupenoid Natural which is non-toxic, conditions the brush fibers, has a slightly citrus smell (and that only a delicate one as opposed to the others). Also, I have discovered that a wash of it has a sligh luster (yet dries as fast as other solvents). If you use turpentine or Turpenoid, or other mineral spirits, simply be sure you have good ventilation and you may want to keep wrags soaked in them in a closed container. But use caution, regardless. They are flammable.