Hair coloring is a process used to color human hair. It is used for a variety of purposes; most commonly to return gray hair to its previous color, to change hair color to a shade regarded as more desirable, or to return hair to its original color after chemicals (e.g. tints, relaxers, sun bleaching) have discolored it.
Hair coloring products are typically categorized based on the length of time they effect the colored hair. The four most common classifications are 'temporary', 'semi-permanent', 'demi-permanent' (sometimes called 'deposit only'), and permanent. Hair lightening products such as bleaches could be regarded as a sub-set of permanent hair coloring products, as their effects are permanent.
Acid dyes are used to coat the surface of hair, since acid dyes have a low affinity to hair, thus can be removed after a shampoo. The penetration and color strength of temporary hair color can usually be improved by applying a bleaching prior to the application of the hair color. Temporary hair color is available in various product forms including rinses, shampoos, gels, sprays, foams and others. This type of hair color is typically used to give brighter, more vibrant shades or colors such as orange or red, that may be difficult to achieve with semi-permanent and permanent hair color. Temporary color is also used by some teens for events at school and Halloween. This phenomenon is because temporary hair colorants do not penetrate the hair shaft itself. Instead, these dye particles remain adsorb (closely adherent) to the hair shaft and can be easily removed with a single shampooing. However, even temporary hair coloring agents can persist if the user's hair is excessively dry or damaged, conditions that allow for migration of the dye from the exterior to the interior of the hair shaft. While temporary hair color products hold a lesser market than semi-permanent and permanent agents, they have value in that they can be easily and quickly removed without bleaching or application of a different colouring product.
When the tint containing the alkalizing ingredient is combined with the developer (usually hydrogen peroxide), the peroxide becomes alkaline and diffuses through the hair fiber, entering the cortex, where the melanin is located. The lightening occurs when the alkaline peroxide breaks up the melanin and replaces it with new color.
Permanent Color is the best choice for grey hair coverage. It has a oxidizing dye that also uses ammonia and peroxide to lift and deposit the new color, going deep into the hair shaft. The use of ammonia opens the cuticle of the hair to allow the color pigments to penetrate deep into the hair shaft.
The latter technique can be used to create many different effects, from subtle highlights acquired during a day at the beach, to more dramatic looks, such as bold, chunky highlights. The terms most commonly used to describe these techniques are:
Both application techniques can be used with either colour treatments that range from temporary to permanent.
While the majority of hair colouring products are designed to produce natural-looking hair color shades (typically blond, red, brown or black), a minority of hair coloring products are designed to create hair colors not typically found in nature. These are available in almost any color imaginable, including green or fuchsia.
These dyes are typically sold in punk-themed stores (such as comic book and music stores). (By contrast, regular hair colors are sold in drugstores and department stores and through professional beauty suppliers.) Many exotic color shades are blacklight reactive, which suggests that the wearers typically want their hair color to show up under nightclub lighting.
The chemical formulae of exotic colored dyes typically contain only tint, and have no developer. This means that they will only create the bright color of the packet if they are applied to light blond hair. Therefore, the majority with darker hair (medium brown to black) are advised to use a bleaching kit prior to tint application in order to get the full effect of the color. Some people with fair hair may benefit from prior bleaching as well, as the yellow undertones of blonde hair can make blue dye look green, and to make the hair porous to easily absorb the pigments into the hair shaft.
These colors are less permanent, being partially removed with each shampoo, and tend to "bleed" onto other fabric even when dry. Users should anticipate staining of light-colored pillows for a week or so after application.
Additionally, there is ongoing debate regarding more serious health consequences of hair dye usage, including lead poisoning.
Symptoms of these reactions can include redness, sores, itching, burning sensation and discomfort. If any of these symptoms occur, alert your hair colorist immediately so that they can remove the color. Symptoms will not always be present right at the application and processing of the dye but can also arise after hours or even a day.
To help prevent (of rather, limit the extent of) allergic reactions, the majority of hair color products recommend that the client conduct a patch test before using the product. This involves mixing a small quantity of dye and applying it directly to the skin. If irritation develops, manufacturers recommend that the client not use the product. A skin patch test is advised before the use of every colouring process, since allergies can develop even after years of use with no reaction.
Adverse reactions can result from both at-home and salon hair coloring, as similar chemicals are used in either setting.
In some cases, allergic reactions are caused by the aniline derivative and/or p-Phenylenediamine (PPD) found in permanent hair color.
In the United States, there have been successful law suits against hairdressers who caused clients' hair to break off.
This discoloration is temporary; it will disappear as the skin naturally renews itself and the top layer of skin is removed. This typically takes a few days or at most one week.
Some of the things that can cause unintended results include:
In the event of unfortunate unintended results, an immediate visit to a professional hair colorist is generally recommended.
There is ongoing debate regarding more serious health consequences that may result from use of hair coloring.
Recent publications regarding the dangers of hair tints include:
It has been recorded historically that ancient civilizations dyed their hair using plants. Some of the most well known are henna, indigo, Cassia obovata, senna, turmeric and amla. Others include katam, black walnut hulls, and leeks .
Presently, there are some companies that do sell alternate based dyes for people that are sensitive to PPD, a chemical found in most hair colors.
There are also said to be safer products that avoid the side-effects of most industrial tints. The safer alternatives generally contain fewer potentially toxic compounds or are plant based, and do also have temporary, semi-permanent and permanent options. However, these products typically do not last as long as industrial tints. Users should be cautioned that allergic reactions are possible even from these "natural" vegetable dyes.
Henna is a plant that is also used for ayurvedic hair coloring. The red dye is commonly used as a deposit-only hair color whose active component, lawsone, binds to keratin and is therefore semi-permanent, but it will wash out with time, generally a couple of months. While "natural" henna is generally a deep red-color, variations exist. These variations, however, usually contain ingredients from other plants and even synthetic dyes.
Using a plant-based color, specifically henna, can cause problems later when trying to do a perm and other permanent hair color. Many people have the misconception that discoloration can occur on hair that has been previously tinted with henna and that hennaed hair cannot be curled. This is untrue, as long as pure imported body art quality henna is used; whereas store-bought "boxed" henna is often mixed with harmful additives, which can cause damage or discoloring to hair. Although it may not be visible on darker hair, the staining from henna will remain for several months and may only show up when trying to lighten hair, and a definite orange tone will appear which will be impossible to remove.