If you have the slider allows your brush to control allow multiple polygroups to be edited on a given stroke but with less intensity then cut into the model.
Once a mesh has been selected it will show in the Mesh Insert Preview thumbnail a cube is shown in the illustration above. The Backface Masking Curve gives you even more control over the effect. You can invert the effect by setting Cavity Masking Intensity slider to a negative value. Press Backface Masking when working with thin-edged models.
