The brush as an artist’s tool has been in use for thousands of years, possibly even as far back as 40,000 years ago in cave paintings. The first brushes were sticks and reeds with mashed ends, then natural hair was incorporated, and as human industry and technology progressed, so too did the sophistication of the brush.
The typical modern brush has three components: the bristle or hair, the ferrule, and the handle. The bristle refers to the hairs as a component, not the type of hair it may be. The ferrule is a metal (exceptions include quill brushes, which use plastic or goose quill) sheath that holds the hairs in place and to the handle. The handle is usually made of wood or plastic.
Easily the most influential factor of a brush’s handling properties is the bristle, both the shape the bristle is made into and what sort of hair the bristle is composed of.
Some of the most common shapes of brushes are as follows:
Round: Bristles are in a round arrangement coming to a point. A very versatile shape, both fine detail and larger coverage are possible.
Flat: Bristles in a rectangular format. Suitable for large coverage. Also, the thin edge and corners can contribute to finer details.
Filbert: A flat brush with a rounded edge, made in an effort to meet rounds and flats halfway. Useful for coverage and soft blending.
Bright: A flat brush with shorter bristles, making for a stiffer brush. Suitable for lifting and scrubbing, and short, sharp marks. A more precise brush than the flat.
Liner: Similar to a round brush, but longer and thinner. Useful when making continuous lines and for fine detail.
Fan: Bristles spread out into a namesake shape, good for blending and textural effects.
The type of hair used to make a brush dictates what medium it is best suited for. Factors that influence this determination include the absorbency of the brush, its ability to retain its shape, and its ability to release paint.
With watercolor, the two most prized aspects of a brush are its softness/”thirstiness” (good for carrying lots of fluid paint), and its “spring” (ability to readily snap back to its original shape). One of the most prestigious hairs for watercolor brushes is that of the Kolinsky Sable, which excels in the two aforementioned traits, and with proper care, can last a long time. Other natural hairs good for watercolor include red sable hair (similar to kolinsky, less costly), squirrel hair (which is extra absorbent), and other soft hairs, like camel, goat, etc. Synthetic brushes are also widely available for watercolor, all are made to replicate/emulate natural hair characteristics.
A note on Gouache: Though gouache is very similar to watercolor in handling and composition, because the pigments are often not as finely milled and whiteners like chalk are added, gouache can be harsher on brushes, so it is recommended that synthetic brushes are used, as they do not wear down as quickly, and when their hairs get frayed, they can be straightened again in hot water.
For acrylic paint, stiffer synthetics are recommended, that way the brush has enough strength to push heavier bodied paint, but still have enough absorbency to handle thinner washes. Natural hog bristle softens in water, so while the stiffness it offers may be appealing, synthetic hair is still the best choice for acrylic.
In oil painting, the consistency in which the painter is working often changes, so a variety of brush hairs are often necessary. Stiffer brushes can be made of hog bristle, and are excellent for moving thick paint around. Softer brushes made of sable can be effective for techniques involving thin layers, like glazing, as well as detail work. Synthetic alternatives for both varieties are available and quite comparable.
A note on Water-Miscible Oils: When painting with water-miscible oil paints, because water can be added to the paints, hog bristle brushes are not recommended. A slightly softer, more absorbent synthetic is advised, as it will carry the water better. It is believed that the use of fine natural hair for water-miscible oils should be discouraged, as it can gum up the hairs. When dried, this paint is difficult to remove from the brush. Please note – there is less information on this relatively new medium, and artists are still finding out its characteristics and tendencies.
Ink, having more or less the same consistency as watercolor when thinned, works nicely in conjunction with watercolor brushes. Also in the tradition of ink painting are what are often referred to as “sumi” brushes. These brushes originate from Asia in their design, often having a handle made of bamboo, and hair from horse, samba, deer, sheep, goat, weasel, badger, or cat. Often, the hairs are arranged concentrically, wherein the slightly stiffer hairs comprise the core of the brush and the center of the point, with the softer hairs ringing the outside. These hairs are very absorbent, so the brush can hold a high volume of ink, but they do not as readily retain their shape, so the artist needs to understand that each stroke can change the shape of the brush, and utilize this characteristic.
With encaustic painting, the main concern for brushes is their ability to withstand extreme heat. Synthetic brushes are for the most part made of nylon which will burn and melt, rendering them unsuitable. Natural hair brushes are the best choice, and “hake” style brushes provide a brush that is of soft, natural hair and cost-effective. Also, because of the heat factor, it is advisable to use hake brushes which do not contain a metal ferrule OR one where the hairs are glued to the handle, since the metal will heat and glue can melt if the brush gets hot enough.
Egg Tempera can be used with brushes normally associated with watercolor, as the medium is traditionally applied in thin, delicate layers. Any sort of soft hair will do, but the artist must be vigilant in ensuring no tempera dries on the brush, as it becomes insoluble in water when dry, and nefariously difficult to clean. With Casein (milk-based tempera), watercolor brushes are also fine, but synthetics are generally recommended, as casein can be harsh on brushes and wear them down faster over time.
Good brush care practices are essential to ensure a long-lived and healthy brush. A good rule-of-thumb process for brush maintenance, for most mediums*, is as follows: 1) Remove all paint from brush, by water, solvent, pinching, etc. 2) Mix the brush in brush soap (many varieties, all should explicitly state their use for brush care), and let sit. After a minute or so, (or longer, depending on the state of the brush) peel the gobs of soap out using fingers. 3) Rinse brushes in water, dry.
*When painting in media that is forever water-soluble, like watercolor, brush soap is not necessary, simply rinsing in water should suffice.
If painting in oils, you may consider letting your brush soak in oil (linseed, safflower, etc.) before using soap, to soak out excess paint and keep brushes supple.
Don’t throw away brushes!
Eventually, all brushes get old and wear down. It’s sad when it happens, but it is a natural part of the brush life cycle. But it’s not the end! A brush with a mashed tip, split hairs, or some other malady is still useful. It can be used for interesting textural effects, scrubbing, or applying materials you might normally consider too hazardous for your nice brushes.
The Future of Brushes:
Recent innovations in technology and manufacturing have brought a wealth of advancements to artist brushes. For watercolorists, especially those who like their paint kits portable, “aqua” brushes are now widely available, these are synthetic brushes with a hollow, removable handle, which can be filled with water that is let out through the brush tip.
Developments with synthetic materials have made a higher quality of brush more available at lower prices, and provide quality substitutes for those who do not want to work with natural hair. Digital brushes that are made with metallic filaments to imitate the feel of a traditional brush, along with new software that can mimic the visual texture of brush marks, continue to further bridge analog and digital art. But the traditional paintbrush will still endure, the tactile delight it offers is still just as enjoyable as it was 40,000 years ago.