ZBrushCentral

Not smooth extract with mask

Hi Everyone!
So i in learning process to sculpting character and also the cloth, and i have a problem. As you can see, i tried to make extruction (?) to make the edge of the cloth (i wish you understand what i mean), i do it with mask by holding ctrl and then extract it with subtool > extract. i get what i want but it look like not smooth (so many wave on the edge). So how to mask it smoothly without the wave ? or i shouldn’t do it with mask ? any better way to achieve the extruction on the edge of the cloth?