Fan brushes are used in areas where full coverage of a larger surface is desired. They are available in a variety of sizes and shapes and hold a large amount of underglaze. Select a fan brush that contains a mix of hair, including ox hair and hake, with bristles cut in different lengths. Natural hair bristles are preferable to synthetic bristles for their ability to hold the weight and consistency of the underglaze without damage.
Detail or spotter brushes are small, round brushes with short bristles that come to a point. Use these to create small details that require no brush strokes, such as dots or small spots, by just touching the tip of the brush to the surface. For finer detail, dilute the underglaze slightly. Do not overfill the brush to avoid dripping and to keep the paint out of the ferrule, or metal head of the brush.
Use a liner brush for filling in small areas. These are round and narrow, with long bristles that come to a point. Load the brush until it is almost dripping and let a drop fall into the center of the area to fill in small areas. Then use the tip of the brush to gently push the color toward the edges of the area. Use small liner brushes to draw fine details and flowing lines. Use just the tip of a large liner brush to repeat a stroke on more than one area without constantly refilling the brush.
Create straight or wavy bands of color with shader brushes. These are available in many sizes and widths. They are flat and have short, straight bristles. Select brushes with dense bristles to hold a larger quantity of underglazing medium. The shader brush is used to fill in both large and smaller areas with bands of color. A chiseled edged shader brush will create strokes that can vary from narrow to broad with a simple turn of the brush.
Round brushes adapt to many uses in underglazing. They are round with short bristles that come to a point, and are available in a variety of sizes. Use them to create lettering and narrow bands of color. Round brushes also allow you to achieve painterly strokes with varying widths that end in a narrow point. Use round brushes to spatter color underglazing by loading the brush with a thin glaze. Hold the brush several inches from the work and brush your fingertip across the bristles. For flicking the glaze, hold the brush away from the work and flick your wrist quickly. This technique can be used to create a drip effect.