Hair colouring
From Wikipedia, the free encyclopedia
Hair colouring products generally fall into four categories: temporary, semipermanent, deposit only/demi, and permanent. All these hair color products, except for temporary color, require a patch test before application to determine if the client is allergic to the product.
"Hair lightening," referred to as "bleaching" or "decolorising," is a chemical process involving the diffusion of the natural color pigment or artificial color from the hair. This process is central to both permanent hair color and hair lighteners.
All "permanent" haircolor products and lighteners contain both a developer, or oxidising agent, and an alkalizing ingredient as part of their ammonia or an ammonia substitute. The purpose of this is to:
- raise the cuticle of the hair fibre so the tint can penetrate,
- facilitate the formation of tints within the hair fibre,
- bring about the lightening action of peroxide.
When the tint containing the alkalising ingredient is combined with the developer (usually hydrogen peroxide), the peroxide becomes alkaline and diffuses through the hair fibre, 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.
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[edit] Temporary hair color
The pigment molecules in temporary hair color are large and, therefore, do not penetrate the cuticle layer, allowing only a coating action that may be removed by shampooing. An example of use of temporary hair color is for Halloween costumes or cosplaying.
Acid dyes are used to coat on the surface of hair, since acid dyes have a low affinity to hair, thus can be removed after a shampoo.
Temporary hair color is available in various product forms including rinses, shampoos, gels, sprays, 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. This phenomenon is due to the fact that temporary hair colorants do not penetrate the hair shaft itself. Instead, these dyes remain adsorbed (closely adherent) to the follicle 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 follicle. 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 dye.
[edit] Semipermanent
Formulated to deposit color on the hair shaft without lightening it. This formula has smaller molecules than those of temporary tinting formulas, and is therefore able to penetrate the hair shaft. Has no developer, may be used with heat for penetration. It also lasts longer than temporary hair color, keeping intact up to 8-14 shampoos.
[edit] Demipermanent
Uses a mild, creamy developer of a lower volume [3 to 7 volume or 1 to 3% H2O2] than permanent color. Lasts 2 to 3 months. Some demi products contain MEA's [an ammonia substitute] which helps with penetration and can lift natural color, but not seriously. Penetrates the hair shaft slightly, leaves hair shiny, covers/blends some grey.
The American Board of Certified Haircolorists and most major manufacturers of hair color now say one should color the new growth area with a permanent color to cover gray and touch up or refresh the ends and length of the hair with a compatible shade of demipermanent color to protect the condition of the hair.
Most hair color manufacturers offer a demipermanent hair color tube and a permanent hair color tube within their product line. However, lately, some hair color manufacturers like Compagnia Del Colore from Italy have possibly come up with a better and more cost-efficient solution for hair colorists. By using an activator or 7 Volume Peroxide (2.1% H2O2) you can now use the same permanent hair color tube and convert it into a semipermanent hair color tube.
If one is using a demi-permanent hair color, especially one that is not of a natural tone, they should be cautioned. While the color may cover some gray hair, on blonde it is known to give the appearance of gray as the color fades.
[edit] Permanent
This is mixed with developer and remains in the hair shaft until new growth of hair occurs. However, despite its being called "permanent", it will fade some over time and with washing. It's used to match, lighten, and cover grey hair. "Permanent" hair color generally contains ammonia, oxidative tints, and peroxide. The allergic reaction that comes from hair dye is generally one of sensitisation to p-phenylenediamine (PPD). The reaction will most likely occur each time one dyes one's hair and will probably get worse each time. The sensitisation from the ingredients in hair color can extend to sensitisation of other products of same or similar composition, including but not limited to the dye used in textiles, sunscreen, rubber, and/or certain medications.
Henna is a deposit-only hair color whose active component, lawsone, binds to keratin and is therefore permanent. Henna may be removed with mineral oil; however, it is considered "permanent" because it does not wash out with shampoos or rinses. It is often mixed with other plant dyes, such as indigo, turmeric, and senna, to change the color. Allergy to henna is much rarer than allergy to permanent hair colors. It is also considered a conditioning treatment.
Using a plant-based color, specifically henna, can cause problems later when trying to do a permanent wave (perm) and other permanent hair color. Discoloration can occur on hair that has been previously tinted with henna; hennaed hair typically cannot be curled. Breakage could also be an issue.
[edit] Special effects
Special effects include highlighting and vivid, unusual hair colors such as green or fuchsia. Highlighting can range from temporary to permanent, using the techniques listed above and a special application process. The techniques required to apply highlighting can be difficult for an individual to perform upon him/herself. One can create looks that range from subtle highlights acquired during a day at the beach, to more dramatic looks, such as bold, chunky highlights.
The more exotic, bright dyes typically contain only tint, and have no developer. These are typically sold in punk-themed stores (such as comic book and music stores), but are rarely available at commercial hair dressers. Colors range from blood red to seafoam green. Many shades are blacklight reactive. Individuals with darker hair (medium brown to black) are advised to use a bleaching kit prior to tint application for 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. These dyes are less permanent, 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.
[edit] Problems related to coloring hair
When coloring one's hair, it is always advisable to visit a professional hair colorist as there are many mistakes a person could make, as well as some serious consequences. The following are some of the problems that may occur as a result of applying hair color:
- Different color outcome compared to what was expected
- Breakage of hair strands
- Loss of hair
- Dry scalp
[edit] See also
- Human physical appearance
- Hairstyle
- Hair highlighting
- Severe allergic reactions
