What did they use in the early/mid 1900s to lighten hair ex. Jean Harlow, Kim Novak, Marilyn Monroe?

Until the early 1900s, hair coloring was made from a wide range of herbal and natural dyes. Flying in the face of other chemists who found the development of hair coloring trivial and unworthy of their time, French chemist Eugene Schuller created the first safe commercial hair coloring in 1909. His invention was based on a new chemical, paraphenylenediamine, and provided the foundation of his company, the French Harmless Hair Dye Company. A year later, the name was changed to one that is more familiar today -- L'Oreal. L'Oreal, one of the hair product giants, has grown steadily over the years; the company credits advanced and applied research of new product development and expansion into markets around the world with its global success.