After the movies success Hughess team established a  chain of "Platinum Blonde clubs" in several cities and offered a $10,000 prize that would go to any hairdresser who could copy Harlows shade. Though Harlow denied her hair was bleached, the platinum blonde color was reportedly achieved with a weekly application of ammonia, Clorox bleach, and Lux soap flakes. This process weakened and damaged Harlows naturally ash-blonde hair.During the 1930s Lawrence M. Gelb advanced the formulas of the bleaching products. In 1950 Clairol, the company Gelb founded with wife Jane Clair, introduced the first one-step hair dye product that lightened hair, which became a huge success with the masses. Bleaching process
Using bleaching agents
Melanin pigments, which give hair a darker color, can be broken down with oxidation. Most commercial bleaching formulas contain hydrogen peroxide and persulfate salts, which under alkaline conditions created by ammonia or monoethanolamine can bleach the hair. Persulfate salts, in combination with hydrogen peroxide or alone, is known for its ability to degrade organics, after activation with heat, transition metals, ultraviolet light, or other means that produce the sulfate radical. Without activation, the persulfate anion is known to react with some organic chemicals, although with slow kinetics. When melanin is oxidized, oxygen gas is released. Products for bleaching ones hair at home usually contain a 6% solution of hydrogen peroxide, while products for use in a hair salon can contain up to 9%.
Hair bleaching, is the practice of lightening the hair color mainly for cosmetic purposes using bleaching agents. Bleaching can be done alone, combined with a toner, or as a step for further hair coloring. The most common commercial bleaching agents in use are hydrogen peroxide and persulfate salts, but historically other agents such as sulfuric acid, wood ash, lye and hypochlorite bleach were used. Hair can also become bleached unintentionally, such as through sun exposure. History
During the early years of the Roman Empire, blond hair was associated with prostitutes. The preference changed to bleaching the hair blond when Greek culture, which practiced bleaching, reached Rome, and was reinforced when the legions that conquered Gaul returned with blond slaves. Sherrow also states that Roman women tried to lighten their hair, but the substances often caused hair loss, so they resorted to wigs made from the captives hair. The bleaching agent used by the Roman women was composed of a solution of ashes from burnt nuts or plants.Diodorus Siculus, a 1st century BC Greek historian, described in detail how Celtic people bleached their hair: "Their aspect is terrifying... They are very tall in stature, with rippling muscles under clear white skin. Their hair is blond, but not naturally so: they bleach it, to this day, artificially, washing it in lime and combing it back from their foreheads. They look like wood-demons, their hair thick and shaggy like a horses mane.