 Backruns watercolors painting techniques & more...
Backruns
Backrun
(also called blossoms, blooms, oozles, watermarks, backwashes or runbacks). Because the hydrophilic and closely spaced cellulose fibers of the paper provide traction for capillary action, water and wet paint have a strong tendency to migrate from wetter to drier surfaces of the painting. As the wetter area pushes into the dryer, it plows up pigment along its edge, leaving a lighter colored area behind it and a darker band of pigment along an irregular, serrated edge. Backruns can be subtle or pronounced, depending on the consistency of the paint in the two areas and the amount of moisture imbalance. Backruns can be induced by adding more paint or water to a paint area as it dries, or by blotting (drying) a specific area of the painting, causing the wetter surrounding areas to creep into it. Backruns are often used to symbolize a flare of light or the lighting contour on an object, or simply for decorative effect.
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Paint Diffusion
Because of osmotic imbalance, concentrated paint applied to a prewetted paper has a tendency to diffuse or expand into the pure water surrounding it, especially if the paint has been milled using a dispersant (surfactant). This produces a characteristic feathery, delicate border around the color area, which can be enhanced or partially shaped by tilting the paper surface before the water dries, shaping the diffusion with surface water flow. |
Pouring Color
Some artists pour large quantities of slightly diluted paint onto separate areas of the painting surface, then by using a brush, spray bottle of water and/or judicious tilting of the painting support, cause the wet areas to gently merge and mix. After the color has been mixed and allowed to set for a few minutes, the painting is tipped vertically to sheet off all excess moisture (the lighter colors across the darker ones), leaving behind a paper stained with random, delicate color variations, which can be further shaped with a wet brush or added paint while the paper is still wet. A popular variation uses separate areas of red, yellow and blue paint, which when mingled and drained produce a striking effect of light in darkness; areas of white are reserved by first covering them with plastic film, masking tape or a liquid latex resist. (The technique was actually invented, and used for similar effect, by J.M.W. Turner.)
Dropping In Color
In this technique a color area is first precisely defined with diluted paint or clear water, then more concentrated paint is dropped into it by touching the wet area with a brush charged with paint. The added paint can be shaped by tilting or stroking; backruns can be induced by adding pure water or concentrated paint, or the color can be lightened by wicking up paint with a moist brush. A striking, tesselated effect is produced when many precisely defined and interlocking areas are separately colored with this randomly diffusing technique.
Salt Texture
Grains of coarse salt, sprinkled into moist paint, produce small, snowflake like imperfections in the color. This is especially effective when the color area is a wash that displays the texture more clearly. It should be remembered when using salt that salt will rot the paper eventually. A similar effect can be produced by spraying a moist (not shiny but still cool to the touch) paint area with water, using a spray bottle held two or three feet above the painting surface, or by sprinking a wet paint with coarse sand or sawdust.
Watercolor painters also learn to apply paint to paper and then, when the paint has dried to the right point, brush along the edge of the paint with a flat, mop or sky brush charged with a moderate amount of clear water.
This new area of water pulls the wet paint outward in a diffusion fan that is controlled by judging the wetness of the paint and the amount of water applied; if excessive water is used, this brushing produces both an outward diffusion and a backrun into the drying paint. This method is useful to produce transitions in value or color within narrow bands, such as the locks of hair in a portrait head.
Scumbling
Scumbling (in the 19th century, called "crumbling color" or "dragging color") is an unrelated technique of loading a large, moist flat or round brush with concentrated paint, wicking out the excess, then lightly dragging the side or heel of the tuft across the paper to produce a rough, textured appearance, for example to represent beach grass, rocky surfaces or glittering water. The amount of texture that can be produced depends on the finish or tooth of the paper (R or CP paper works best), the size of the brush, the consistency and quantity of the paint in the brush, and the pressure and speed of the brush stroke. Moist paper will cause the scumbled color to diffuse slightly before it dries.
Diluting and mixing watercolor paints
When using watercolors, it is important to use the full range of paint consistency. The densest possible color is obtained by using the paint as it comes from the tube. The lightest color is obtained by using paint heavily diluted with water, or applied to the paper and then blotted away with a paper towel. Generally, paint directly from the tube should be used only with drybrush application: if the paint is used to completely cover the paper it typically dries to a dull, leathery appearance (called bronzing). Usually one part tube paint must be diluted with 2 to 3 parts water to eliminate bronzing in paint applied with a large brush to dry paper; with 4 to 6 parts water to produce the most saturated color; and with still more water to produce delicate tints of color and to enhance pigment textures (granulation or flocculation). The main point is to take advantage of the complete range of paint effects that are produced at different paint consistencies.
Tube paints are normally used with a flat palette that provides compartmentalized paint wells (for holding separate paint colors) and a large mixing area for mixing or diluting paints; pan paints are arrayed in enameled metal paint boxes that provide shallow mixing areas in the folding cover or in a fold out faceted tray. With tube paints, the excess paint remaining in the palette paint wells should be cleaned out only if the paint has become dirtied with another paint; otherwise the paints should be allowed to dry out promptly and completely, as this prevents mold from forming. Despite the common misconception, there is no visual difference between the viscous paint packaged in tubes and the dried paints in pans. Tube paints left to dry in paint wells are used in exactly the same way as pan paints -- the painter simply drips or sprays water over the paint a few minutes before starting work. The only notable difference is that some tube paints, such as viridian or cerulean blue, produce a gritty, uneven paint mixture when left to dry and then rewetted.
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