Q:  How do you remove nail polish on children's clothes?

A:  I’m sorry I don’t have better news, but unfortunately nail polish is permanent when it gets on fabric.  For hard surfaces like fingernails, a weak acetone solution (i.e. nail polish remover) can dissolve nail polish, but textile fibers don’t respond the same way.  There are so many crevices that trap and absorb the polish – within the fibers, as well as in the spaces between the fibers where they are spun into yarns and woven/knit into fabric. 

Just to satisfy my curiosity, I let some nail polish dry on an old cotton t-shirt.  I applied nail polish remover directly to the stain and blotted it with a cotton ball. Hardly any nail polish was removed.  A stronger acetone solution (something from a hardware store) might be more effective, but then you’d have the problem of a solvent soaked shirt that needs to be disposed of safely to prevent spontaneous combustion.  Hopefully the children’s clothes can find another use, like art class or gardening or some other activity.