Foil highlighting is the process of using foil to separate strands of hair which will be lightened from strands of hair which will remain its natural color.
The process is done by applying lightener to the hair that has been woven and separated using an applicator brush.
The foil is then folded to protect the hair and surrounding area during the "processing" time.
This is the amount of time required to achieve the desired results. In highlighting hair, hydrogen peroxide mixed with pigment is used to change the color of the strand.
This process is also used in applying "lowlights" to the hair. In this process, hair dyes are used to create strands of hair that are darker than the natural color.