How do you unshrink your jeans?

Preshrinking is done with heat. so when I preshrink cotton material, i wash it in super hot water and dry it in a very hot dryer. I usually preshrink at least twice before cutting out my material to sew. Just a note: Cotton will shrink everytime it is washed and dried if you are washing in hot water and drying. After the initial preshrink, I will wash my cottons in cold water and dry in medium heat. Don't be afraid to wash in cold water. There is detergent out there that works great in cold.