Young Juan and Milagros are models of a Photographer who tells Juan to first kiss the girl (He kisses her forehead). He is then ordered to drag down her pants as he snaps another shot. When he is ordered to drag down her panties, he is about to do it, but Milagros push him back as he scared runs away.
Bellocq decides to photograph her in the nude. Here is where her "coverings" are most evident; she appears to be genuinely nude except for a triangle shaped piece of gauze covering her private parts.