Adapting oil paint for various function and effect

Oil painting is usually discussed through color: mixing pigments, building an image and deciding what belongs beside what. But oil paint is also a physical material. It can be transparent or opaque, glossy or matte, nearly liquid or thick enough to preserve the shape of a brushstroke.

Mediums are one of the main ways painters control those qualities.

An oil painting medium changes how paint behaves. It can make paint flow more easily, become more transparent, hold additional texture or dry differently. This means the same tube of oil color can produce an extremely smooth glaze in one part of a painting and a rough, sculptural surface somewhere else.

One of the simplest materials is refined linseed oil. Linseed oil is already the traditional binder in many oil paints, and adding a small amount can make stiff paint more fluid and easier to move with a brush. It can lengthen a stroke and make the surface feel less resistant. Blick describes Gamblin Refined Linseed Oil as useful for thinning oil colors and making custom painting mediums.

Stand oil is related, but behaves differently. It is linseed oil that has been thickened through heating. The material is viscous, but it also encourages paint to level, producing smoother passages with fewer visible brush marks. It can also increase transparency, which makes it useful for glazing.

A glaze is simply a transparent or semi-transparent layer of color placed over another layer. Instead of mixing the two colors together on the palette, light travels through the upper layer and interacts optically with what is beneath it. A dark glaze can deepen an already painted passage without completely covering it. A warm transparent layer can shift the feeling of a cooler painting while allowing the original structure to remain visible.

Modern alkyd mediums can produce similar fluid and transparent effects while changing drying time. Gamblin Galkyd, for example, increases fluidity, levels brushstrokes and speeds the drying of oil color. These kinds of mediums are useful when the goal is not necessarily to create obvious texture, but to control how paint moves and how one layer sits over another.

Texture can also move in the opposite direction.

Impasto is oil paint applied thickly enough that the surface itself begins to have relief. A brushstroke remains physically present after the brush is gone. A palette knife can leave a ridge. Highlights can project slightly from the surface and catch real light rather than only depicting it.

An impasto medium allows a painter to extend paint while preserving that body. Winsor & Newton Liquin Impasto Medium is formulated to add body, preserve crisp marks and extend oil color. A painter can mix it into ordinary tube paint and then push, drag or knife the mixture across the surface.

This changes the painting in a literal sense. The work is no longer only an image on a flat plane. Its surface begins to have geography.

Another option is cold wax medium. Cold wax thickens oil color while creating a more matte surface. Gamblin's version combines beeswax, alkyd resin and odorless mineral spirits into a soft paste that can be mixed with oil paint.

Cold wax can make oil painting feel substantially different. Paint becomes shorter and more resistant. It can be spread with a knife, scraped back, layered again and partially removed. Rather than trying to hide the history of the painting process, a wax-based surface can preserve it.

That opens another category of texture: subtraction.

Paint does not always have to be added. A wet surface can be wiped with a rag, scraped with a palette knife or scratched with the end of a brush. Scratching through a wet layer to reveal something beneath is often called sgraffito. A painted line is created by depositing material; a sgraffito line is created by removing it.

These approaches can be especially interesting when combined with oil sticks.

The terminology is worth clarifying. A conventional oil pastel and an oil paint stick are not quite the same material. Oil pastels generally contain a non-drying oil and remain workable rather than curing into the same kind of paint film as traditional oil paint. For painting directly into an oil painting, what is often more useful is an oil stick, oil bar or pigment stick.

R&F Pigment Sticks are essentially professional oil color made solid enough to hold in the hand. They are made with pigment, linseed oil and natural waxes. Instead of squeezing paint onto a palette and transferring it with a brush, the painter can place the oil color directly onto the painting.

That creates a strange and useful intersection between drawing and painting.

A pigment stick can be used almost like an enormous crayon. A light stroke can skip across the weave of a canvas and leave broken color. More pressure can create a dense, opaque mark. The side of the stick can cover a broad area. A sharp edge can produce a more controlled line.

But the mark is still oil paint. It can immediately be brushed. It can be pushed with a palette knife. It can be blended into wet tube paint. It can be scraped back. Another color can be drawn directly through it.

A painter might draw a heavy red line across a canvas and leave one section untouched so that it retains the physical quality of drawing. Another section could be pulled outward with a dry brush. A third section could be softened with medium until the original line disappears almost completely into the surrounding paint.

The movement between those states is what makes oil sticks particularly interesting. Drawing does not have to remain drawing. A mark can begin as a line and gradually become a painted field.

R&F also makes Oil Blending Mediums specifically for its Pigment Sticks. The mediums are designed to increase transparency, aid blending and create glazing effects. Blick sells both liquid versions and colorless blending sticks.

A colorless stick is an especially interesting idea because it allows a painter to manipulate oil color through the physical action of drawing without introducing another pigment. A colored mark can be spread or made more transparent. Hard edges can become soft. Thick passages can dissolve into thinner ones.

The surface of an oil painting can therefore be constructed through several different kinds of decisions at once.

Paint can be made more fluid with linseed oil. Stand oil can help produce smoother, more transparent passages. Alkyd mediums can alter flow and drying. Impasto mediums can preserve thick marks. Cold wax can create matte, resistant surfaces that invite scraping and layering. Pigment sticks can place oil color directly into the painter's hand.

And none of these approaches needs to govern the entire painting.

A single work can contain a thin transparent beginning, conventional brushwork, areas polished almost smooth, palette-knife impasto, waxy matte passages, scratched lines and raw marks drawn directly with an oil stick. That is part of what makes oil painting unusually expansive as a medium. The painter is not only selecting colors. They are deciding what the paint itself should become.