Wool bleached with nonstabilized hydrosulfite in the presence of sodium (SLS) had significant increases in the whiteness index accompanied by decreases in the yellowness index. These wools also have a cysteine content which is up to 30% lower than wools bleached without the surfactant. The disulfide linkage is protected by the unsalted fixation of the surfactant. The net charge on the keratin increases as a result of SLS fixation, making the disulfide less accessible to reducing anions.