Realist painters paint "things" - ordinary, or not-so-ordinary, people, places, and objects. Realist painting has certain parameters, the most obvious being the representation of some aspect of a universally accepted visual reality. Abstract painting does not attempt to represent an accurate (or semi-accurate) depiction of visual representation, but, like realism, is dependent on the basic visual elements of line, shape, value, and color.
A good painting, whether realist or abstract, should be able to use the visual elements of line, shape, value, and color to create pattern, unity, variety (including a variety of edges), texture, rhythm, and movement. This is art language.
Too often realist paintings default to the representation of objects as sufficient. This is unfortunate, since painting is so much more than trying to make "something look like something". A realist painting, just like an abstract painting, needs to be about art language. A painting should have unity and variety within an overall pattern of art information.
Some paintings are more explicit in pattern, and some less so. Some use color extensively, some use value, and some paintings use both. No matter how the visual elements are used, a painting needs to engage us in a way that is visually interesting, and a realist painting needs to use art information that is, at the very least, as important as the "things" that it is portraying.
Seeing and painting variety in edges is one of the major stumbling blocks realist painters encounter. Too many painters think edges are some kind of arbitrary flourish instead of an inherent part of three-dimensional reality and an integral part of visual language.
If we think we see "things" as having hard edges everywhere, it is only because our visual system is designed to notice differences instead of being attuned to subtle changes. A painter needs to learn to see differently and to look for the variety in edge information to be able to convincingly use edges as transitions between value, shapes and color.
Three realist painters who were masters of edge interpretation are Joaquin Sorolla, Anders Zorn, and John Singer Sargent. All three created object paintings, while still using art information as their vehicle. Sorolla used color in a different way than Sargent and Zorn and his use of color created additional problems for edge modification.
Simply put, it's easier to transition neutral colors from one shape to another, than it is to transition obvious color changes, such as warmer color (red, orange, yellow) to cooler color (blue, violet). A warmer color next to a cooler color will emphasize an edge, somewhat like a light color next to a dark color will emphasize an edge. So a warmer color next to a cooler color will always contain a visual separation (or edge) even when the values are equal.
Because Sorolla's paintings are so color dependent, it is easy to separate objects, or figures from ground. One could just take a pair of scissors and cut all the pieces out. However, and this is important, ask yourself why his paintings maintain unity and work as an interesting visual whole?
