The foundation of oil painting lies in the ability to effectively manipulate and mix pigments, a skill that offers the painter expansive creative control over the final image. Mixing oil paint is the process of combining pigments to achieve a specific hue (pure color), along with the correct value (lightness or darkness), and the desired chroma (purity or intensity). Mastering this combination allows the artist to translate the colors observed in the world onto the canvas with precision and nuance. This foundational knowledge influences the visual impact of any oil painting.
Essential Tools and Palette Setup
Before beginning the physical act of mixing, the right tools and an organized workspace are necessary for an efficient painting session. The primary tool for combining oil paint is the palette knife, which is far superior to a brush because its stiff, non-absorbent blade ensures pigments are thoroughly incorporated without paint getting lodged near the ferrule. Using a brush for mixing can cause paint to build up at the base of the bristles, making the brush stiff and difficult to clean, which shortens its lifespan. A palette knife, conversely, is easily wiped clean, preserving the integrity of the paint mixture and the longevity of the artist’s brushes.
The surface where the paint is mixed is also significant, with materials like glass, sealed wood, or disposable paper offering a substantial area for working. Organizing the pigments on this palette should be done systematically to build muscle memory and increase speed during the painting process. Most artists arrange their colors along the edge of the palette, typically following a logical sequence such as the color wheel, or organizing them from light to dark, or by warm and cool temperatures.
The center of the palette must be kept clear to provide an ample, clean space for the actual mixing of colors. Arranging the colors consistently, with the white paint often placed a short distance from the others, allows the artist to locate and access specific pigments without distraction. This consistent layout minimizes wasted time and paint, as the artist develops an intuitive understanding of where each color is located.
Step-by-Step Color Mixing Techniques
The physical process of mixing color should begin by considering the tinting strength of the pigments being used, which is the power of a color to dominate a mixture. Since darker colors generally possess a much greater tinting power than lighter hues, it is most efficient to start with a generous pile of the lighter color and incrementally add small amounts of the darker, stronger color. Adding too much dark pigment at once can quickly overpower the mixture and necessitate using a large volume of the lighter color to compensate, resulting in wasted paint.
To achieve the precise color, the artist must simultaneously control the hue, value, and chroma. Value (lightness or darkness) is adjusted by adding white to create a tint, or by adding a darker color like black or an earth tone to create a shade. Chroma (intensity) is reduced by adding a color’s complement on the color wheel. For instance, adding a small amount of green to a red mixture will dull its intensity without drastically altering its value.
The physical technique for mixing with a palette knife involves gathering the paint into a mound, then using the knife to repeatedly fold the paint over itself and scrape it flat. This action, done rapidly and repeatedly, ensures that the pigment particles are uniformly dispersed throughout the oil binder, creating a consistent color. Once the color appears correct on the palette, a small amount should be tested by applying a thin swipe onto a clean area or against the painting surface. This small test provides an immediate and accurate assessment of how the mixed color will interact with the surrounding painted areas.
Adjusting Paint Consistency with Mediums and Solvents
While mixing pigments controls the color, solvents and mediums are used to alter the working properties, such as the flow, texture, and drying time of the oil paint. Solvents, such as turpentine or odorless mineral spirits, primarily function to thin the paint, making it more fluid for thin washes and underlayers, and are also utilized for cleaning brushes and tools. Using too much solvent, however, can “break” the paint film by dissolving too much of the oil binder, potentially leading to a brittle, unstable layer that will not adhere properly.
Mediums, including linseed oil, poppy oil, or alkyd-based mediums, are added to the paint to enhance flow, increase gloss, and adjust the drying rate. Adding linseed oil will increase the paint’s “fatness,” making it more flexible and increasing its drying time, while alkyd mediums accelerate the drying process. These additives should be incorporated carefully, by adding just a few drops at a time to the mixed pile of paint, rather than mixing them into the raw pigment from the tube.
When working in layers, the “fat over lean” principle is necessary for ensuring the longevity of the painting. This rule dictates that each successive layer of paint should contain more oil, or be “fatter,” than the layer beneath it. Paint layers with a higher oil content dry slower and are more flexible. Applying a fat layer over a lean, fast-drying layer prevents the surface from cracking as the lower layer continues to cure and contract over time.