You can block off an area on a surface so it is not affected by the Artisan operations you apply to it. Unselected vertices act as a block.

To restrict an area for painting

1. Select the vertices you want to paint. For details, see the Basics guide.
2. Select an Artisan tool.
3. Paint the surface with the selected Artisan tool. Any brush strokes you make over the selected vertices affect only the selected vertices. Unselected vertices are masked and are unaffected by your painting, as shown in the following example.