The hair fiber contains very small amounts of elements such as sodium, potassium, magnesium, calcium, strontium, zinc, iron, manganese, mercury, cadmium, lead, arsenic, selenium, silicone and phosphorous. The overall amount of these trace elements is less than 1%. These elements may have been incorporated during the synthesis of the hair follicle and are internal to the hair. However, some of these trace elements may be on the surface of hair due to environmental pollution. During the straightening of curly hair fibers with No – Lye relaxers that consist of a mixture of calcium hydroxide and guanidine carbonate, hair fibers adsorb significantly higher levels of calcium ions. These ions tend to make the hair surface dry, dull, and rough in feel (Akhter & Syed, 2003)[i].
[i] H Akhtar and AN Syed. (2003). Hair relaxer system and method therefor. Patent No. 6,602,493, assigned to Avlon Industries, Inc.