Re: Hair Coloring
Nadia Grubb
Hair coloring, or hair dyeing, is the practice of changing the color of the hair on humans' heads. The main reasons for this are cosmetic: to cover gray or white hair, to alter hair to create a specific look, to change a color to suit preference or to restore the original hair color after it has been discolored by hairdressing processes or sun bleaching.
Hair coloring can be done professionally by a hairdresser or independently at home. Hair coloring is very popular, with 50-80% of women in the United States, Europe, and Japan having reported using hair dye.[1] At-home coloring in the United States reached sales of $1.9 billion in 2011 and was expected to rise to $2.2 billion by 2016.[citation needed][needs update]
The dyeing of hair is an ancient art that involves treatment of the hair with various chemical compounds. In ancient times, the dyes were obtained from plants.[4] Some of the most well known are henna (Lawsonia inermis), indigo dye, Cassia obovata, senna, turmeric and amla. Others include katam (buxus dioica), black walnut hulls, red ochre and leeks.[5] In the 1661 book Eighteen Books of the Secrets of Art & Nature, various methods of coloring hair black, gold, green, red, yellow, and white are explained.[6] The development of synthetic dyes for hair is traced to the 1860s discovery of the reactivity of para-phenylenediamine (PPD) with air.[7] Eugne Schueller, the founder of L'Oral, is recognized for creating the first synthetic hair dye in 1907.[8] In 1947 the German cosmetics firm Schwarzkopf launched the first home color product, "Poly Color".[9] Hair dyeing is now a multibillion-dollar industry that involves the use of both plant-derived and synthetic dyes.[10]
Henna is an orange dye commonly used as a deposit-only[further explanation needed] hair color whose active component, lawsone, binds to keratin. It is therefore considered semi-permanent to permanent, depending on a person's hair type. Most people will achieve a permanent color from henna, especially after the second dye. With repeated use the orange color builds up into red and then auburn. While "natural" henna is generally a red color, variations exist. These variations usually contain ingredients from other plants and even synthetic dyes.
Indigo is natural dye from a plant (Indigofera tinctoria, I. suffructicosa, or I. arrecta) that can be added to henna or layered on top of it to create brown to black colors in the hair. Henna is orange, and indigo is blue, so as complementaries on a standard color wheel, the two colors' combined effect is to create brown tones. Like henna, indigo may fade after one application, but it becomes permanent on the hair with repeated use.
Using a plant-based color such as henna can cause problems later when trying to do a perm or permanent synthetic hair color, as some store-bought henna in addition contains metallic salts which react to hydrogene peroxide. This reaction may lead to unpredictable results, such as unwanted greenish or blueish tones. These added metallic salts also can cause skin irritation. Pure henna and purely plant-based mixes of henna, indigo ("black henna"), walnut hulls etc. without such addition are commercially available, too.
In 2018, a system for making semi-permanent hair dyes from renewable waste blackcurrant (Ribes nigrum L.) fruit skins from the fruit pressing industry was developed. Anthocyanin pigments were extracted from the blackcurrant skin waste[11] and formulated into hair dyes. The dyes showed high buildup on hair and gave an intense blue color, which was stable to multiple washes.[12]
Permanent hair color generally contains ammonia and must be mixed with a developer or oxidizing agent in order to permanently change hair color. Ammonia is used in permanent hair color to open the cuticle layer so that the developer and colorants together can penetrate into the cortex.[13] The developer, or oxidizing agent, comes in various volumes. The higher the developer volume, the higher the "lift" will be of a person's natural hair pigment. Someone with dark hair wishing to achieve two or three shades lighter may need a higher developer whereas someone with lighter hair wishing to achieve darker hair will not need one as high. Timing may vary with permanent hair coloring but is typically 30 minutes or 45 minutes for those wishing to achieve maximum color change.
(244 shampoos typically) Demi-permanent is hair coloring that contains an alkaline agent (e.g. ethanolamine, sodium carbonate) other than ammonia, and while always employed with a developer, the concentration of hydrogen peroxide in that developer may be lower than used with a permanent hair color. These products provide almost no lightening of hair's color during dyeing, since the alkaline agents employed in demi-permanent colors are less effective in removing the natural pigment of hair than ammonia. As the result, they cannot color hair to a lighter shade than it was before dyeing and are less damaging to hair than their permanent counterpart.
Demi-permanents have several advantages as compared with permanent color. Because there is essentially no lifting (i.e., removal) of natural hair color, the final color is less uniform/homogeneous than a permanent and therefore more natural looking; they are gentler on hair and therefore safer, especially for damaged hair; and they wash out over time (typically 20 to 28 shampoos), so root regrowth is less noticeable and if a change of color is desired, it is easier to achieve. Demi-permanent hair colors are not permanent but the darker shades in particular may persist longer than indicated on the packet.
(62 shampoos typically) Semi-permanent hair coloring cannot lighten the hair either. Because it involves no developer (hydrogen peroxide) or ammonia, it is thus less damaging to hair strands than their demi-permanent counterpart.
There will be subtle variations in shade across the entire head, because of hair's color and porosity along the length of a hair strand. The final color of each strand of hair will depend on its original color and porosity. This variation gives a more natural looking result than the solid all over color of a permanent. Because gray or white hairs have a different starting color than other hair, they will not appear as the same shade as the rest of the hair when treated with semi-permanent color. If there are only minimal grey/white hairs, the effect will usually be enough for them to blend in, but as the gray spreads, there will come a point where it will not be disguised as well. In this case, the move to demi-permanent as a base can be used sometimes adding highlights, to delay permanent coloring.
Semi-permanents may still contain the suspected carcinogen p-phenylenediamine (PPD) or other related colorant carcinogens. The U.S. Environmental Protection Agency reported chronic exposure to PPD in the diet of rats and mice depressed body weight of the animals, with no other clinical signs of toxicity observed in several studies.[14]
Temporary hair color is available in various forms including rinses, shampoos, gels, sprays, and foams. Temporary hair color is typically brighter and more vibrant than semi-permanent and permanent hair color. It is most often used to color hair for special occasions such as Christmas and Halloween costume parties.
The pigments in temporary hair color cannot penetrate the cuticle layer of the hair. The color particles remain adsorbed (closely adherent) to the surface of the hair shaft and are easily removed with a single shampooing. Temporary hair color can persist on hair that is excessively dry or damaged in a way that allows for migration of the pigment to the interior of the hair shaft.Some plants can be used for temporary coloring, too, e.g. bete juice.
Alternative hair coloring products are designed to create hair colors not typically found in nature. These are also referred to as "vivid color" in the hairstyling industry. The available colors are diverse, such as the colors green and fuchsia.Permanent alternatives in some colors are available. More recently, blacklight-reactive hair dyes have been brought to market that fluoresce under blacklights, such as those often used at nightclubs.
The chemical formulae of alternative color 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. Darker hair (medium brown to black) would need to be bleached in order for these pigment applications to take to the hair desirably. Some types of fair hair may also take vivid colors more fully after bleaching. Gold, yellow and orange undertones in hair that has not been lightened enough can muddy the final hair color, especially with pink, blue and green dyes. Although some alternative colors are semi-permanent, such as blue and purple, it could take several months to fully wash the color from bleached or pre-lightened hair.
Hair is given a lighter color by bleaching it. Melanin pigments, which give hair a darker color, can be broken down with oxidation.[15] The oxidizing agent used to bleach hair is hydrogen peroxide.[15] It is mixed with ammonia to create an alkaline solution and to speed up the reaction.[15] When melanin is oxidized, oxygen gas is released.[15]
Peroxide bleached hair can have undesirable brassy or yellow hue. A product known as a toner is used to slightly alter the hair color's undertones.[16] Purple shampoo (shampoo with purple coloring agents) can also be used to counteract brassy undertones.[17]
Hair coloring can involve the use of chemicals capable of removing, replacing, and/or covering up pigments naturally found inside the hair shaft. Use of these chemicals can result in a range of adverse effects, including temporary skin irritation and allergy, hair breakage, skin discoloration and unexpected hair color results. According to the International Agency for Research on Cancer (IARC), in vitro and in vivo studies (in exposed human populations) have shown that some hair dyes and many chemicals used in the hair dyeing process can be considered mutagenic and carcinogenic.[18][19]
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