Oil paints, a combination of a drying oil like linseed or walnut oil and a dry powdered pigment, have been use by artists for thousands of years. But it is only in the since the Renaissance period that they have been used extensively, mostly because of the advantages provided by the discovery of solvents like turpentine that allowed them to be thinned, and mixed with resins.
Although acrylic paints have taken over some of the ‘market share’, oils are still popular and it is because they are beautiful and versatile in ways that are unmatched by any other medium.
Because there are certain technical issues associated with the properties of oil paints, artists concerned with permanence must be mindful of a few principles that will ensure that their expressions last for future generations to enjoy.
- Paint on a good quality ground (gesso) that is thick enough to prevent oil seeping through to the support.
- Paint on a rigid rather than a flexible support whenever possible (see #19).
- Paint fast dryers under slow dryers.
- Paint ‘lean’ (low oil content) pigments under ‘fat’ (high oil content) ones.
- When painting in layers keep the under layers thinner and leaner.
- Paint oils over acrylics if you must but not the other way around.
- Do not paint over a layer that has a dry skin but is soft and wet underneath.
- Oil paint can be thinned with only small very amounts of solvent.
- Do not add extra oil to your paint.
- Use a good alkyd painting medium to thin paint for making glazes and veils.
- Use Retouch varnish sparingly.
- Keep the underpainting light and bright (see # 17&18).
- Do not apply the paint too thick.
- Heavy texture and collage effects are best done with acrylic paints and mediums.
- Do not use old paint that has begun to dry and is stiff and rubbery, it will not adhere well.
- Paint around things rather than over top unless you want the underpainting to show (see # 17&18).
- Remember that oil paint darkens and becomes more yellow/brown with age.
- Remember that oil paint becomes more transparent with age.
- Remember that oil paint becomes more hard and brittle with age.
- Use soap to clean hands and brushes, not solvents.
- Wait between 3-12 months before applying picture varnish, depending on the thickness of the paint.
- Do not hang or store oil paintings where they will be exposed to humidity or large temperature fluctuations.
- Never use water to clean an oil painting.
- Use the best quality paints you can afford.
- Do not mix low grade and professional grade paints in the same painting.