Monthly Archives: April 2012

Emma Stone is Blonde Again: The Science of Hair Dyes


Earlier this month, 23-year-old actress Emma Stone changed her look from sassy redhead to bombshell blonde, surprisingly her natural color.  Emma began the process of lightening her famously fiery red hair in March when she went strawberry blonde.  She has since completed the peroxide process with a return to near-platinum locks.

In previous posts we have discussed that excess hair coloring can cause hair loss, but in this post we will discuss how lightening your hair can cause necrosis (death) of the scalp.

What Exactly Is Hair?

Typical mammalian hair consists of the shaft, protruding above the skin, and the root, which is sunk in a follicle, or pit, beneath the skin surface. Except for a few growing cells at the base of the root, the hair is a unique tissue composed of keratin and related proteins. The hair follicle is a tubelike pocket of the epidermis, that encloses a small section of the dermis at its base. Human hair is formed by rapid divisions of cells at the base of the follicle. As the cells are pushed upward from the follicle’s base, they harden and undergo pigmentation.

The hair on our scalps and in our eyebrows and eyelashes are different from other bodily hairs. The hair on our heads grows a healthy .5 inch per month, and long scalp hairs have an average life of 3 to 5 years. Most of us have between 100,000 and 150,000 hairs on our heads!

There are two kinds of melanin found in the hair: eumelanin (the most common and responsible for hair shades from brown to black) and phaeomelanin (responsible for yellowish-blond, ginger and red colors). Absence of pigment produces white/gray hair. Before any permanent color can be deposited into the hair shaft, the cuticle, or outer layer, must be opened. The insoluble formula then reacts with the cortex to deposit or remove the color

Coloring/Tinting/Dyeing the hair is a chemical process of adding color to the hair shafts. 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 Schueller created the first safe commercial hair coloring in 1907. 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.

The two main chemical ingredients involved in any coloring process that lasts longer than 12 shampoos are:

  • Hydrogen peroxide (also known as the developer or oxidizing agent) — This ingredient, in varying forms and strengths, helps start the color-forming process and creates longer-lasting color. The larger the volume of the developer, the greater the amount of sulfur is removed from the hair. Loss of sulfur causes hair to harden and lose weight. This is why, for the majority of hair coloring, the developer is maintained at 30% volume or less.
  • Ammonia — This alkaline allows for lightening by acting as a catalyst when the permanent hair color comes together with the peroxide. Like all alkalines, ammonia tends to separate the cuticle and allow the hair color to penetrate the cortex of the hair.

In addition, various types of alcohols, which can also dry the hair, are present in most hair color. The hydrogen peroxide is the main culprit for initiating inflammatory skin reactions on the scalp.

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