Category:Hair

Hair (both human and animal) is comprised mainly of a protein, keratin, the fibers of which give the inner core of hair a great deal of strength. Hydrogen bonds and disulfide bonds link the chained amino acids that make up hair. Hydrogen bonds break and re-form easily on exposure to water, but disulfide bonds (responsible for curl, among other properties), can be broken only via chemical means. Under examination with a microspectrophotometer, scientists have discovered that high heat, UV exposure, and even artificial lighting can be quite damaging to human hair. Wool, too, suffers in the sun—the fleece of sheep allowed to spend too much time in the sun before shearing accepts little dye when sheared from their backs, compared to their underbellies, as a result of disulfide bonds broken by UV light. Heat and a wide variety of insects, too, are deleterious to woolen textiles. Wool has a high resistance, however, to fungi and bacteria, provided it is free from sizing and soaps; further, wool can absorb three times its volume in water and requires a bit of humidity to remain viable.