Hair can hold together by inner glue. Hair has outside layer {epicuticle}, which has no glue. Thioglycolate solution softens glue, to allow hair reshaping by wrapping hair around rollers held by pins {perm} {permanent wave}|. Chemicals {neutralizer} re-harden glue. After drying, you remove rollers. Bleached and dyed hair loses some epicuticle and is easier to perm. Children's hair and thin hair do not have enough inside hair material to set hair well.
Hair grows straight if it has circular cross-section but curls if it has oval cross-section. Hair grows 15 to 30 centimeters each year.
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Date Modified: 2022.0224