Unfortunately, there is little consistency between brush manufacturers as to what these sizes actually are, so the size of a No. 10 in one brand can be different from a No. 10 in another brand. If you’re buying brushes from a catalog or online and it’s a brand you’re not familiar with, check to see if there’s an indication of the actual width of the brushes in inches or millimeters. Don’t just go by the brush size number. If you’re painting with watercolor or very fluid paint, a thick brush will hold considerably more paint. This enables you to paint for longer without stopping. But if you want a brush for dry-brush techniques, you may well want a brush that holds less paint. The handle of a brush is most often made from wood that’s painted or varnished, but it can also be made from plastic or bamboo. The length is variable, from really short (such as those in travel paint boxes) to really long (ideal for big canvases). What’s more important than length is that the brush feels balanced in your hand. You’re going to be using it a lot, so it needs to be comfortable to hold. What bristles or hairs are in a brush is also variable, depending on what the brush is intended for. Most important is that they’re firmly held and aren’t going to fall out constantly as you paint. The ferrule is the part that holds the handle and hairs together and in shape. It’s usually made from metal, but not exclusively. Mop brushes, for instance, can have a ferrule made of plastic and wire. A decent-quality ferrule won’t rust or come loose. The toe of a brush is the very end of the bristles, while the heel is where the bristles go into the ferrule at the end of the handle (not that you can usually see this without taking a brush apart). The belly is, as the name would suggest, the fattest part of a brush. (It’s most obvious on a round brush, rather than a flat one.) A substantial belly on a round watercolor brush enables you to pick up a large quantity of paint at a time. If the filbert has hog or bristle hairs, they will wear down with use. The photo shows the front and side views of a very old filbert and a brand-new, never-used one. A filbert is a favorite brush shape for many because it can produce such a variety of marks. The No.10 filbert is commonly used. Don’t throw away worn-down filberts: use them for dry brushing and you won’t have to worry as you bash the hairs to spread them out. The round brush in the photo has synthetic hair in it, and didn’t have a very fine point even when it was brand-new. But such a brush is useful for creating broad brushstrokes as it’s very soft and holds a good quantity of fluid paint. Always consider what you intend to do with the brush; don’t have unrealistic expectations of it or you’ll just frustrate yourself—and blame your tools for poor painting. A flat brush’s paint carrying capacity is determined by the bristles it has and by their length. A short-haired, synthetic-bristle flat brush will hold less paint than a long-haired, mixed or natural-hair brush. The flat brush in the photo has hog hair, which holds paint well and, being stiff, is ideal for leaving brushmarks in paint should you wish to do so. By rotating the brush in your hand as you move it across the surface, and by lowering or raising it, you get fluid, calligraphic mark making. If you hold the brush loosely in your hand and move across the surface quickly, letting it do what it wants to some extent, you get a free, expressive mark. This is great for branches in trees, for instance.
Stippling (spreading out small dots or short dashes)Highlights in hair, as it helps produce the illusion of individual hairsSmoothing and blending out brushstrokesPainting a tree or grass
A waterbrush is ideal for using with watercolor paints and watercolor pencils, including lifting color directly from them. Various manufacturers produce waterbrushes, in a few sizes, and in either a round or flat shape. If your local art store doesn’t stock them, many online art stores do. Waterbrushes are useful for on-site sketching, together with a small travel watercolor set, as it eliminates the need to take a container with water. To clean the brush, simply squeeze it gently to encourage more water to flow out, then wipe it on a tissue. It doesn’t take much water to clean the brush, but it’s also easy to refill the waterbrush’s reservoir from a tap or a bottle of water. Different brands work slightly differently. Some have an easier, continuous flow of water and others require a definite squeeze to get water out. It is generally not recommended to fill waterbrushes with dilute watercolor nor with calligraphy ink, since both may clog up the brush. Depends on the brand of the waterbrush (and particle size in the ink) it may be possible to fill the brush with sepia ink without problems. A waterbrush doesn’t hold as much pigment as a sable watercolor brush since the bristles as synthetic, so you’ll find yourself picking up color more often. The bristles are also prone to staining (as you can see in the photo), but that’s hardly unique to a waterbrush. A waterbrush makes painting from a dark to a light color really simple: Keep painting and the extra water thins the paint until eventually all that’s left is water. But these brushes also make painting large areas an even tone trickier than with a conventional brush. A varnishing brush isn’t going to wear out in a hurry, so you won’t have to replace it very often. A good varnishing brush helps ensure you get a smooth coat of varnish. And by using it only for varnish, it will never get tainted by paint. You’re looking for a flat brush which is at least a couple of inches (5 centimeters) wide, about a third of an inch (1 centimeter) thick, and has long hairs. These can be either synthetic or natural hair, but either way should be soft with a bit of spring. You don’t want a “scratchy” brush that will leave brush marks in the varnish. Check that the hairs are well anchored, that they’re not going to keep falling out as you apply the varnish. Larger art material stores and online art stores should stock a range of varnishing brushes. Pick them up and see how comfortable they feel in your hand. Alternatively, look in your local hardware store—though you may want to cut off some of the hairs to reduce the thickness of the brush, and be sure to avoid cheap DIY brushes whose hairs will almost certainly fall out regularly.