Q. Question 7: Does blond hair have only pheomelanin (yellow and red)? If so, why does it bleach out so easily knowing that pheomelanins are much harder to bleach out than eumelanin (black melanin)?

A. All human hair types at early stages of life contain the two types of melanin you mentioned. There is no hair type with only one type of melanin. Dark hair has a higher percentage (99%) of eumelanin and a much lower percentage of pheomelanin (about 1%). Blond hair still has about 95% of eumelanin and about 5% of pheomelanin. Of course dark hair has a much higher overall amount of melanin (eumelanin and pheomelanin) than blond hair.

Let us look at some numerical examples without putting much emphasis on the numbers because they are strictly hypothetical:

If we assume that a dark hair strand has 10,000 "molecules" of total melanin, then 9900 "molecules" of these (99%) would be eumelanin and 100 "molecules" (1%) would be pheomelanin. In comparison, a blond hair strand of equal size may have only 100 "molecules" of melanin. Of these, 95 "molecules" are eumelanin (95%) and 5 "molecules" are pheomelanin (5%). When both dark and blond hair types are bleached, most of the accessible eumelanin in the two types of hair would be broken down and only very little of the pheomelanin would do so. The reason why pheomelanin is harder to bleach is because it has sulfur linkages that make the molecule more tightly packed and inaccessible to the bleach. The end result is that dark hair bleaches to a brassy undertone because of the significant amount of pheomelanin left behind, while blonde hair reaches the palest yellow stage because only very few pheomelanins were there to start with.

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