If you want to remove curls or waves on human hair, you can straighten it with large rollers. The larger the rollers, the straighter the hair will be.

To roller-set hair straight:
1. Make sure the wig is securely blocked.
2. Wash the hair or wet it thoroughly, if the hair is already clean.
3. Take a section of hair at the center front and roll it on an jumbo roller. Secure the roller with a T-pin or roller pin.
4. Continue rolling the hair on jumbo rollers, working from the front of the wig back toward the nape of the neck. Do this until all of the hair is rolled. The rollers should all remain parallel to each other.
5. Let the wig dry naturally or put the wig into a wig dryer.
6. Take the rollers out and brush through the hair. This method does need yield super-straight hair created by flat iron, but instead hair that is mostly straight with a slight amount of bend. This is a more natural straight-hair look than one you will get from flat-ironing hair.