There are many ways to create masks in ZBrush, you can create rectangular masks, circular masks, and pattern masks manually, but these masks are fixed shapes. Using the Lasso mask in the ZBrush enables irregular graphic masks to be created with ease.
Draw a matte using the Lasso tool
There is a lasso tool at the lowest end of the right shelf, and we can also use the tool to frame the mask range.
Activating the Lasso tool, holding down the CTRL key, and selecting from the blank area of the view to the object, an irregular black marquee appears, and the marquee range is determined to release the mouse to mask, as shown in.
Or you can't find the Lasso tool in the ZBrush navigation bar, you can also press and hold the Ctrl+shift key, select the irregular line in the Dragrect, or you can hold down the CTRL key and click the brush icon, you will see a variety of lasso, and then choose according to your needs. Then hold down the CTRL key to draw the mask area.
Remove the lasso tool to draw a matte
The use of masks to delete the parts of the object is actually more use in the organism and other irregular form, more flexible, you can first mask the area, and then, select the Visablity panel in the hidept.
Then, then into the Subtool panel, and then to the lowest level, point split hidden, after the separation, how to delete the line, and the original object is reserved level and detail.
ZBrush Tutorial: http://www.zbrushcn.com/support.html
How to draw a matte using the lasso tool in ZBrush