The Paint Mixer Brush is pre-loaded with the Primary color selected on the Color panel. As you drag on the page, this color blends with the color of pixels underneath the stroke, giving a smudged appearance to the image.
By default, the mixed color remains on the Paint Mixer Brush. However, the brush can be manually 'cleaned' at any time. As soon as you drag on the page with a clean brush, the brush will pick up the color directly underneath it.
Alternatively, the mixed color can be manually removed from the brush at any time and reloaded with the Primary color. You can also set this to occur automatically every time you begin a new stroke.
With the Paint Mixer Brush selected, do any of the following: