Several tools in Softimage use a brush. These include:
The Paint tool (W) for painting parameter weight maps (see Weight Maps [Scene Elements]) and envelope weight maps (see Envelopes [Character Animation]), as well as Push Paint which is a special case of using a weight map to drive a Push deformation (see Paint Push [Modeling and Deformation Basics]).
The Paint Vertex Color tool for painting vertex colors, also known as Color at Vertices or CAV properties. See Vertex Colors [Scene Elements].
The Paint selection tool (F11) for selecting points, edges, or polygons. See Paint Selection Tool [Scene Elements].
All brush-based tools have similar options and workflows:
Click and drag to "paint". Look at the mouse status line to see the effects of the different mouse buttons.
While the tool is active, press R and drag the mouse to change the brush radius. For additional ways to set the radius, see Changing the Brush Radius.
While the tool is active, press E and drag the mouse to change the opacity. The opacity controls how much weight is added or removed with each stamp of the brush. A number at the bottom of the viewport indicates the current opacity setting.
To modify other brush properties, press Ctrl+W or choose Get 
Property Map Paint Tools Brush Properties from any toolbar. See Brush Properties Property Editor [Properties Reference].
The Paint tool is used to paint weight maps and envelope weights.
When painting in normal or additive mode (the default):
To remove weight, either use the right mouse button or press Shift+left mouse button.
To smooth weight values between deformers, press Alt+left mouse button.
You can change modes using the Brush Properties Property Editor [Properties Reference], or on the weight paint panel.
When using a brush-based tool, you can set the radius interactively or by increments. Alternatively, you can also set the radius in the Brush Properties Property Editor [Properties Reference].
To increase or decrease the brush radius by increments
While a brush-based tool is active, do either of the following to change the radius by increments of 10% of its current size:
Press the up arrow key to increase the radius or the down arrow key to decrease it.
Scroll the mouse wheel forward to increase the radius or backward to decrease it. This works only if you are not using the mouse wheel to zoom — see Mouse Wheel in Camera Preferences [Preference Reference].
