Using textured brushes, you can create an infinite range of fuzzy, textured and watercolour lines. You can use bitmap brush tips, adjust your line's hardness and opacity, combine two tips and apply a paper texture to your brush strokes so as to adapt the Brush tool to a variety of art styles and create natural-looking brush strokes.
When drawing on a vector layer, brushes are solid vector brushes by default. You can however create a textured vector brush which combines both Harmony's vector and bitmap drawing capabilities. You can tweak textured vector brush strokes using various vector editing tools such as the Contour Editor, the Smooth Editor, the Perspective and the Envelope tools, and Harmony will resample the textures inside your brush strokes with each modification.
If you are drawing on a bitmap layer, your brush is always textured. You can configure a textured brush to look crisp and solid if desired, but brush strokes on a bitmap layer cannot be tweaked or smoothed.