How to Set Up Dry Brush Dynamics in GIMP

Configuring custom brush dynamic force variations in GIMP allows digital artists to replicate the scratchy, textured aesthetic of traditional dry brush painting. By mapping dynamic parameters like pressure, velocity, and force to the brush's opacity, size, and hardness, you can simulate paint depleting from coarse bristles as you stroke across the canvas. This guide provides a direct, step-by-step workflow for creating and fine-tuning a custom Paint Dynamic preset optimized for dry brush effects.

1. Create a New Paint Dynamic

  1. Open GIMP and navigate to Windows > Dockable Dialogs > Paint Dynamics.
  2. At the bottom of the Paint Dynamics dialog, click the Create a new dynamics button (the blank page icon).
  3. The Paint Dynamics Editor will open automatically. Name your new preset (e.g., "Dry Brush Force").

2. Configure the Dynamics Matrix

The Dynamics Matrix connects physical input behaviors (such as stylus pressure or mouse speed) to brush rendering properties. For a dry brush effect, configure the following intersections in the grid:

  • Force / Pressure: Check the box at the intersection of Pressure and Force. This ensures that the simulated friction and bristle contact change dynamically based on how hard you press.
  • Opacity / Velocity: Check the box for Velocity under Opacity. This lowers paint flow as stroke speed increases, producing streaky, broken textures during rapid hand movements.
  • Size / Pressure: Check the box for Pressure under Size to allow bristle splay on heavier strokes.
  • Hardness / Fade: (Optional) Check Hardness under Fade or Pressure to soften edges as the simulated paint runs out.

3. Customize the Dynamic Force Curve

To ensure the force does not respond in a flat, linear way, customize its response curve in the Paint Dynamics Editor:

  1. Locate the drop-down menu at the bottom of the Paint Dynamics Editor and select Force.
  2. Adjust the curve so it starts low and arches upward quickly in the middle-to-high input range. An exponential or S-shaped curve creates a distinct threshold where light strokes produce faint bristle scratches, while firm strokes deposit thick paint.
  3. Select Opacity from the drop-down menu and adjust its velocity curve downward toward the right side. This ensures fast movements dramatically reduce pigment deposition.

4. Optimize Tool Options for Dry Brushing

Once your dynamic preset is configured, adjust your active brush settings in the Tool Options dock:

  • Brush Tip: Select a textured or multi-bristle brush tip, such as Bristles 01, Chalk, or an acrylic splatter tip.
  • Dynamics: Set the Dynamics selector to your newly created "Dry Brush Force" preset.
  • Spacing: Increase brush spacing slightly (typically between 15% and 30%). Higher spacing breaks the continuous flow of the stroke, exposing the underlying canvas texture.
  • Force Slider: Set the base Force slider between 30 and 60 in the Tool Options to prevent the stroke from fully saturating immediately.

5. Test and Refine

Select the Paintbrush Tool (P) and test your stroke on a blank canvas. Vary both your hand speed and stylus pressure:

  • Fast, light strokes should yield gritty, translucent, broken lines.
  • Slow, heavy strokes should apply dense, concentrated color.
  • Return to the Paint Dynamics Editor to tweak the Force and Opacity curves until the resistance matches your preferred drawing style.