No i do not know but i can give you a tip. Use morcain oil for this. So what i usually do is after i bath i usually wait till the hair is almost dry then divide your hair into 2 section. then tie each section into a bun. leave it over night. you might not get use sleeping with the buns at first but after quite some time you will get use to it eventually. then in the next morning, open the buns and tadaa! you have beautiful curls in a natural way without using hot tongs to spoil your hair. what i usually do after opening the buns is, i will put some morcain hair oil to make the curls look shiny and smooth and spray some hair spray to hold those curls in place.