A waterbrush is a painting tool that combines a brush tip with a refillable water reservoir, making it especially useful for watercolor painting, calligraphy, and travel sketching.
 
To use it, begin by unscrewing the handle and filling the reservoir with clean water. Once filled, screw the handle back on securely. To activate the brush, gently squeeze the barrel to allow water to flow into the bristles; the more you squeeze, the wetter your strokes will be, which affects the paint's intensity and transparency.
When it comes to applying paint, you can either touch the brush to dry or moist watercolor pans to pick up pigment or preload the brush by dipping it into watercolor or ink. Paint as you normally would, squeezing occasionally to keep the brush moist or to rinse it between colors.
For cleaning, gently squeeze the barrel while wiping the bristles on a cloth or paper towel until the water runs clear. After use, rinse the brush thoroughly and allow it to dry with the cap off.
 
This is a medium sized brush which is suitable for both detailed work and filling in larger areas.