Limitations to an Oil Painting on a Canvas
- Because oil paints are suspensions of pigment particles in oils, the drying process can take anywhere from weeks to months, mostly depending on the type of oil used. This slow drying time can be seen as either an advantage or a limitation. On the plus side, it facilitates blending and allows the artist to leave his canvas occasionally without fear of its drying up too soon; however, this makes it necessary for work on a single project to stretch for days or weeks. Also, it increases the risk of accidentally blending colors and ruining already-finished sections. Working with blown oils and stand oils speeds up the drying process, but it still takes considerably longer compared to other media. Blown oils have been heated in the presence of air, while stand oils have been heated in an enclosed environment without air exposure. Both process help the oil pigment to dry faster than uncured oil bases, but still take some time to dry out.
- This downside to oils on canvas is mainly due to the flexible nature of the support. Unlike rigid supports – such as wood, fiber/paperboard, glass or PVC – canvas can slacken and stretch significantly as a result of changes in humidity, causing noticeable cracks in the paint and priming. Even in controlled environments, cracking can result when the top layers of paint dry at a faster rate than those beneath; however, this second cause of cracking can be prevented by painting “fat over lean;” that is, every new layer of paint must contain more oil than the previous layers.
- One of the trickiest aspects of oil painting is learning how to mix paints with the right amounts and types of mediums, thinners and solvents to achieve the desired end result. The nature and concentration of these substances will affect the paint’s color, transparency, gloss, consistency and texture when dry. Some popular mediums such as linseed oil have a yellowing tendency, which limit their use for lighter pigments. If the mediums or thinners used are badly proportioned, the pigment may not bind properly, or the dried-up paint may end up wrinkling, crackling or flaking off. Done right, the end result can be spectacular, but the process itself requires a fair amount of precision.
- A painter, having mixed all the colors he needs for a project, cannot afford to use the wrong brush as brushes for oil painting tend to be on the expensive side. A painter needs at least two long-handled brushes for general work: one bristle-hair brush for larger areas and a sable brush for detail. That doesn’t even begin to cover the different brush shapes for different strokes: rounds, brights, flats and filberts (plus varnish brushes for finishing). All these individual brushes can add up to a hefty sum. Horsehair, mongoose hair, and nylon brushes are cheaper alternatives, but none of them can give as good a result as bristles and sables.