Water is powerful, it travels far and fast and through surface tension gathers itself into mass bodies of graceful motion; all the time lifting up lifeless flotsam and jetsam reshaping and sorting it into weights and sizes dispersing it at different levels along its margins.
When pigments are suspended in water they behave in the same way, the individual characteristics of each pigment are exposed by the water. Some finer particles drop straight to the bottom and creep across the surface, some float for a long time pressed into one spot in the center of the water, some spread in tendrils and many migrate outwards, pushing other pigments aside and accumulating at the margins and as the water evaporates they show up as harsh lines at the tight edges of the water mass. These behaviors depend on the sizes and weights of the specific molecules inherent to each individual pigment and the saturation and quantity of water.
These characteristics are what makes watercolour painting such an 'organic' activity and what makes me feel I am dancing with a microcosm of some universal laws of nature when I paint with it.
Oil paint is my current choice of medium. It is more plastic in its response, has less personality than water colour so can be more easily manipulated without such careful planning and attention to technique. This means that rather than utilizing the material's natural characteristics to create a delicate effect, I am free to express a more personal image. In a way this is more of a challenge because water colour, used carefully, creates naturally attractive effects with just the simplest marks and oil paints don't necessarily , they must be carefully manipulated with a specific outcome in mind. So I cannot rely on their characteristics to deliver an interesting and successful image. I need to have an outcome in mind, an idea of what the image is trying to say.