Pen saturation is a value of the pen, introduced in Scratch 3.0. It changes the amount of the pen color's saturation. Lower values make the pen color more gray and higher values make it more saturated. The default value is 100.
The following blocks can be used to affect this value:
set pen (saturation v) to ()— Sets the saturation to a given value.
change pen (saturation v) by ()— Increases the saturation by a given value.