Hair coloring

Hair coloring

Hair coloring is the process of adding pigment to or removing pigment from the hair shaft. Hair coloring processes may be referred to as dyeing or bleaching, depending on whether you are adding or removing pigment.

Temporary hair tints simply coat the shaft with pigments which later wash off.

Most permanent color changes require that the cuticle of the hair be opened so the color change can take place within the cuticle. This process, which uses chemicals to alter the structure of the hair, can damage the cuticle or internal structure of the hair, leaving it dry, weak, or prone to breakage. After the hair processing, the cuticle may not fully close, which results in coarse hair or an accelerated loss of pigment. Generally, the lighter the chosen colour from one's initial hair color, the more damaged it may be. Other options for applying color to hair besides chemical dyes include the use of such herbs as henna and indigo, or choosing ammonia-free solutions

Chemical alteration

Chemical alteration

Chemical alterations like perming, coloring can be carried out to change the perceived quality and texture of hair. All of these are temporary alterations because permanent alterations are not possible.

Chemical alteration of hair only affects the hair above the scalp; unless the hair roots are damaged, new hair will grow in with natural color and texture

Washing

Washing

A quasi-racist advertisement for an electric hairbrush, from 1899

The most effective way to wash hair is to wet the hair then apply shampoo two times, rinsing between each application of shampoo.^{[citation needed]} Apply a small amount of shampoo onto the palm of the hand and rub between palms to get an even coverage. Run through the hair, focusing on the scalp for the first shampoo application and the hair for the second. Some specialized shampoos require a development time for the second shampoo so manufacturer's instructions should be followed.

Following shampooing, towel dry the hair and apply a conditioner to the mid-lengths and ends of the hair. Conditioners should be combed through the hair with a wide tooth comb. Care should be taken when combing because wetting hair breaks the internal hydrogen bonds. Hydrogen bonds give hair its dry strength and help maintain its shape. Develop the conditioner according to manufacturer's instructions and rinse. Note that some conditioners are left on the hair and do not require rinsing.

Microfiber towels that help absorb the water from hair faster than conventional towels are available on the market. These are particularly helpful for those with very thick or damaged hair, that may otherwise take a while to dry.

Western cleaning products and methods

Western cleaning products and methods

A more alkaline rated (meaning a high pH) shampoo is stronger and harsher to one's hair. This can mean that the hair will be left dry and brittle. Shampoos containing citric, lactic or phosphoric acid are most likely balanced. Oily hair might require a more acidic pH shampoo. Anti-dandruff shampoos have been implicated in irritation of the scalp, and an increase in the production of dandruff. Anti dandruff shampoos may be available over-the-counter or on prescription, based on the strength of the medicine. Dandruff, despite common belief, is more often related to too much, or an issue somehow with, sebum production and not dry scalp skin. Not all flakes are dandruff and only a qualified physician can determine not only that one indeed does have dandruff; but also, what type of dandruff one may have. If one is experiencing redness of the scalp skin, bumps on the scalp skin, and any weeping from sores and/or bleeding in addition to flakes, professional medical diagnosis should be sought.

Conditioner choice is greatly dependent upon hair type and hair status, such as colored, permed, dry, and the like. Commercial conditioners contain a variety of ingredients such as plant oils, provitamins, acidic compounds, plastics, stabilizers, thickeners, emulsifiers, and fragrances.

Conditioners may sometimes add weight to hair, creating an adverse effect in the shampooing/conditioning process. Some conditioners, especially those containing a silicone compound, may coat the hair and lead to build up on the hair, making it dull, and lead to harsher shampoo use; in a sense, an endless cycle of shampooing and conditioning. When used correctly, however, conditioners are helpful in temporarily coating the hair to increase shine and ease tangles.

Build up is when the hair has a sticky or gummy feel, the conditioner choice seems to work less well, or the hair may be more prone to tangling. Buildup occurs when the minerals from water and/or products are not rinsed away during shampooing. A clarifying shampoo may be required to remove it. Clarifying removes all things on the surface of the hair strands, essentially leaving the hair without moisture. Failure of conditioning as part of a clarifying hair wash process may lead to excessive drying of hair.

Viable natural ways to condition the hair include rinses with lemon juice, lime juice, vinegar or for brunettes, rosemary tea. The use of acid rinses may assist those who have itchy scalps, depending on the cause for the itchiness. Hair which is lacking sebum may also be softened using plant oils such as olive oil and coconut oil.

Hair cleaning

Hair cleaning

One way to distribute the hair's natural oils through the hair is by brushing with a natural bristle brush. The natural bristles effectively move the oil from the scalp through to the hair's mid-lengths and ends, nourishing these parts of the hair. Brushing the scalp stimulates the sebaceous gland, which in turn produces more sebum. When sebum and sweat combine on the scalp surface, they help to create the acid mantle, which is the skin's own protective layer.

Washing hair removes excess sweat and oil, as well as unwanted products from the hair and scalp. Often hair is washed as part of a shower or bathing with shampoo, a specialized surfactant. Shampoos work by applying water and shampoo to the hair. The shampoo breaks the surface tension of the water, allowing the hair to become soaked. This is known as the wetting action. The wetting action is caused by the head of the shampoo molecule attracting the water to the hair shaft. Conversely, the tail of the shampoo molecule is attracted to the grease, dirt and oil on the hair shaft. The physical action of shampooing makes the grease and dirt become an emulsion that is then rinsed away with the water. This is known as the emulsifying action.

Shampoos have a pH of between 4 and 6 and do not contain soap. Soapless shampoos are acidic and therefore closer to the natural pH of hair. Acidic shampoos are the most common type used and maintain or improve the condition of the hair as they don't swell the hairshaft and don't strip the natural oils. Conditioners are often used after shampooing to smooth down the cuticle layer of the hair which can become roughened during the physical process of shampooing. There are three main types of conditioners. Anti-oxidant conditioners; which are mainly used in salons after chemical services and prevent creeping oxidation, internal conditioners, which enter into the cortex of the hair and help improve the hair's internal condition (also known as treatments), and finally external conditioners, or everyday conditioners, which smooth down the cuticle layer making the hair shiny, comb-able and smooth feeling. Conditioners can also provide a physical layer of protection for the hair against physical and environmental damage.

Hair cleaning and conditioning

Hair cleaning and conditioning

Biological processes and hygiene

Human hair close-up

Care of the hair and care of the scalp skin may appear separate, but are actually intertwined because hair grows from beneath the skin. The living parts of hair (hair follicle, hair root, root sheath, and sebaceous gland) are beneath the skin, while the actual hair shaft which emerges (the cuticle which covers the cortex and medulla) has no living processes. Damage or changes made to the visible hair shaft cannot be repaired by a biological process, though much can be done to manage hair and ensure that the cuticle remains intact.

Scalp skin, just like any other skin on the body, must be kept healthy to ensure a healthy body and healthy hair production. If the scalp is not cleaned regularly, by the removal of dead skin cells, toxins released through the skin or external hazards (such as bacteria, viruses, and chemicals) may create a breeding ground for infection. However, not all scalp disorders are a result of bacterial infections. Some arise inexplicably, and often only the symptoms can be treated for management of the condition (example: dandruff). There are also bacteria that can affect the hair itself. Head lice is probably the most common hair and scalp ailment worldwide. Head lice can be removed with great attention to detail, and studies show it is not necessarily associated with poor hygiene. More recent studies reveal that head lice actually thrive in clean hair. In this way, hair washing as a term may be a bit misleading, as what is necessary in healthy hair production and maintenance is often simply cleaning the surface of the scalp skin, the way the skin all over the body requires cleaning for good hygiene.

The sebaceous glands in human skin produce sebum, which is composed primarily of fatty acids. Sebum acts to protect hair and skin, and can inhibit the growth of microorganisms on the skin. Sebum contributes to the skin’s slightly acidic natural pH somewhere between 5 and 6.8 on the pH spectrum. This oily substance gives hair moisture and shine as it travels naturally down the hair shaft, and serves as a protective substance preventing the hair from drying out or absorbing excessive amounts of external substances. Sebum is also distributed down the hair shaft “mechanically” by brushing and combing. When sebum is present in excess, the roots of the hair can appear oily, greasy, generally darker than normal, and the hair may stick together.

Hair care

Hair care is an overall term for parts of hygiene and cosmetology involving the hair on the human head. Hair care will differ according to one's hair type and according to various processes that can be applied to hair. All hair is not the same; indeed, hair is a manifestation of human diversity.

In this article, 'Hair care' is taken to mean care of hair on the human head, but mention should be made of process and services which impact hair on other parts of the body. This includes men‘s and women’s facial, pubic, and other body hair, which may be dyed, trimmed, shaved, plucked, or otherwise removed with treatments such as waxing, sugaring, and threading. These services are offered in salons, barbers, and day spas, and products are available commercially for home use. Laser hair removal and electrolysis are also available, though these are provided (in the US) by licensed professionals in medical offices or speciality spas.

History

History

Facial tissue has been used for centuries in Japan, in the form of washi (和紙) or Japanese tissue, as described in this 17th century European account of the voyage of Hasekura Tsunenaga:

"They blow their noses in soft silky papers the size of a hand, which they never use twice, so that they throw them on the ground after usage, and they were delighted to see our people around them precipitate themselves to pick them up."^[2]

In 1924 facial tissue as it is known today was first introduced by Kimberly-Clark as Kleenex. It was invented as a means to remove cold cream. Early advertisements linked Kleenex to Hollywood makeup departments and sometimes included endorsements from movie stars (Helen Hayes and Jean Harlow) who used Kleenex to remove their theatrical makeup with cold cream. It was the customers that started to use Kleenex as a disposable handkerchief, and a reader review in 1926 by a newspaper in Peoria, Illinois found that 60 % of the users used it for blowing their nose.^[3]

Kimberly-Clark also introduced pop-up, colored, printed, pocket, and 3-ply facial tissues.^[4]

Facial tissue

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A box of tissues

Facial tissue and paper handkerchief refers to a class of soft, absorbent, disposable papers that is suitable for use on the face. They are disposable alternatives for cloth handkerchiefs. The terms are commonly used to refer to the type of paper tissue, usually sold in boxes, that is designed to facilitate the expulsion of nasal mucus from the nose although it may refer to other types of facial tissues including napkins and wipes.

Facial tissue is often referred to as a "tissue", or by the genericized trademark "Kleenex" which popularized the invention and its use.

Potential health risks

Potential health risks

Main article: Sunscreen controversy

As a defense against UV radiation, the amount of the brown pigment melanin in the skin increases when exposed to moderate (depending on skin type) levels of radiation; this is commonly known as a sun tan. The purpose of melanin is to absorb UV radiation and dissipate the energy as harmless heat, blocking the UV from damaging skin tissue. UVA gives a quick tan that lasts for days by oxidizing melanin that was already present and triggers the release of the melanin from melanocytes. UVB on the other hand yields a tan that takes roughly two days to develop because it stimulates the body to produce more melanin. The photochemical properties of melanin make it an excellent photoprotectant.

Sunscreen chemicals on the other hand cannot dissipate the energy of the excited state as efficiently as melanin and therefore the penetration of sunscreen ingredients into the lower layers of the skin increases the amount of free radicals and reactive oxygen species (ROS).^[5]

Some sunscreen lotions now include compounds such as titanium dioxide which helps protect against UVB rays. Other UVA blocking compounds found in sunscreen include zinc oxide and avobenzone. There are also naturally occurring compounds found in rainforest plants that have been known to protect the skin from UV radiation damage, such as the fern Phlebodium aureum.

Some sunscreen chemicals produce potentially harmful substances if they are illuminated while in contact with living cells.^[26][27][28] The amount of sunscreen which penetrates through the stratum corneum may or may not be large enough to cause damage. In one study of sunscreens, the authors write:

The question whether UV filters acts on or in the skin has so far not been fully answered. Despite the fact that an answer would be a key to improve formulations of sun protection products, many publications carefully avoid addressing this question.^[29]

In an experiment by Hanson et al. that was published in 2006, the amount of harmful reactive oxygen species was measured in untreated and in sunscreen-treated skin. In the first 20 minutes the film of sunscreen had a protective effect and the number of ROS species was smaller. After 60 minutes, however, the amount of absorbed sunscreen was so high that the amount of ROS was higher in the sunscreen-treated skin than in the untreated skin.^[5]

George Zachariadis and E Sahanidou of the Laboratory of Analytical Chemistry, at Aristotle University, in Thessaloniki, Greece, have now carried out an ICP-AES analysis of several commercially available sunscreen creams and lotions. "The objective was the simultaneous determination of titanium and several minor, trace or toxic elements (aluminum, zinc, magnesium, iron, manganese, copper, chromium, lead, and bismuth) in the final products," the researchers say. They concluded that "Most of the commercial preparations that were studied showed generally good agreement to the ingredients listed on the product label." However, they also point out that the quantitative composition of the products tested cannot be assessed because the product labels usually do not provide a detailed break down of all ingredients and their concentrations. They also point out that, worryingly, their tests consistently revealed the presence of elements not cited in the product formulation, which emphasized the need for a standardized and official testing method for multi-element quality control of these products.^[30]

Some epidemiological studies indicate an increased risk of malignant melanoma for the sunscreen user.^{[31][32][33][34][35][36][37][38]} Despite these studies, no medical association has published recommendations to not use sunblock. Different meta-analysis publications have concluded that the evidence is not yet sufficient to claim a positive correlation between sunscreen use and malignant melanoma.^[39][40]

Adverse health effects may be associated with some synthetic compounds in sunscreens.^[41] In 2007 two studies by the CDC highlighted concerns about the sunscreen chemical oxybenzone (benzophenone-3). The first detected the chemicals in greater than 95% of 2000 Americans tested, while the second found that mothers with high levels of oxybenzone in their bodies were more likely to give birth to underweight baby girls.^[42]

The use of sunscreen also interferes with vitamin D production, leading to deficiency in Australia after a government campaign to increase sunscreen use.^[43] Doctors recommend spending small amounts of time in the sun without sun protection to ensure adequate production of vitamin D.^[44] When the UV index is greater than 3 (which occurs daily within the tropics and daily during the spring and summer seasons in temperate regions) adequate amounts of vitamin D₃ can be made in the skin after only ten to fifteen minutes of sun exposure at least two times per week to the face, arms, hands, or back without sunscreen. With longer exposure to UVB rays, an equilibrium is achieved in the skin, and the vitamin simply degrades as fast as it is generated.^[45]

Concerns have been raised regarding the use of nanoparticles in sunscreen.^[46] Theoretically, sunscreen nanoparticles could increase rates of certain cancers, or diseases similar to those caused by asbestos.^[47] In 2006 the Therapeutic Goods Administration of Australia concluded a study and found:

"There is evidence from isolated cell experiments that zinc oxide and titanium dioxide can induce free radical formation in the presence of light and that this may damage these cells (photo-mutagenicity with zinc oxide). However, this would only be of concern in people using sunscreens if the zinc oxide and titanium dioxide penetrated into viable skin cells. The weight of current evidence is that they remain on the surface of the skin and in the outer dead layer (stratum corneum) of the skin." ^[

Differences between sunblock and sunscreen

Differences between sunblock and sunscreen

A tube of SPF 15 sun block lotion

Although it is a common misconception^{[citation needed]} that sunblock and sunscreen are both the same, they are not. They have similar properties and are both important in caring of the skin, sunblock is opaque and is stronger than sunscreen since it is able to block a majority of the UVA/UVB rays and radiation from the sun, thus not having to be reapplied several times a day. Titanium dioxide and zinc oxide are two of the important ingredients in sunblock.

Sunscreen is more transparent once applied to the skin and also has the ability to protect against UVA/UVB rays as well, although the sunscreen's ingredients have the ability to break down at a faster rate once exposed to sunlight, and some of the radiation is able to penetrate to the skin. In order for sunscreen to be more effective the user needs to consistently reapply at least every two hours, and use a higher SPF.^[23]

However, that distinction is mostly used for marketing, and the FDA has in fact considered banning the term "sunblock" from marketing claims as it considers it misleading.^[24]

For total protection against damage from the sun, the skin needs to be protected from UVA, UVB and IRA (Infra Red Energy). Roughly 35% of solar energy is IRA.^[25]

Measurements of UVA protection

Measurements of UVA protection

Persistent pigment darkening (PPD)

The persistent pigment darkening (PPD) method is a method of measuring UVA protection, similar to the SPF method of measuring UVB light protection. Originally developed in Japan, it is the preferred method used by manufacturers such as L'Oreal.

Instead of measuring erythema or reddening of the skin, the PPD method uses UVA radiation to cause a persistent darkening or tanning of the skin. Theoretically, a sunscreen with a PPD rating of 10 should allow you to endure 10 times as much UVA as you would without protection. The PPD method is an in vivo test like SPF. In addition, Colipa has introduced a method which, it is claimed, can measure this in vitro and provide parity with the PPD method.^[20]

The UVA seal used in the EU

As part of revised guidelines for sunscreens in the EU, there is a requirement to provide the consumer with a minimum level of UVA protection in relation to the SPF. This should be a UVA PF of at least 1/3 of the SPF to carry the UVA seal. The implementation of this seal is in its phase-in period, so a sunscreen without it may already offer this protection.^[21]

[edit] Star rating system

In the UK and Ireland, the Boots star rating system is a proprietary in vitro method used to describe the ratio of UVA to UVB protection offered by sunscreen creams and sprays. Based on original work by Prof. Brian Diffey at Newcastle University, the Boots Company in Nottingham, UK, developed a standard method which has been adopted by most companies marketing these products in the UK. The logo and methodology of the test are licenced for a token fee to any manufacturer or brand of sunscreens that are sold in the Boots retail chain, provided the products to which the logo is applied perform to the standard claimed. Own Label products exclusively sold in other retailers are now excluded from the terms of the licence. It should not be confused with SPF, which is measured with reference to burning and UVB. One-star products provide the least ratio of UVA protection; five-star products are best. The method has recently been revised in the light of the Colipa UVA PF test, and with the new EU recommendations regarding UVA PF. The method still uses a spectrophotometer to measure absorption of UVA vs UVB; the difference stems from a requirement to pre-irradiate samples (where this was not previously required) to give a better indication of UVA protection, and of photostability when the product is used. With the current methodology, the lowest rating is three stars, the highest being five stars.

In August 2007, the FDA put out for consultation the proposal that a version of this protocol be used to inform users of American product of the protection that it gives against UVA ^[22]

Sun protection factor (SPF)

Sun protection factor (SPF)

Two photographs showing the effect of applying sunscreen in visible light and in UVA.

The sun protection factor of a sunscreen is a laboratory measure of the effectiveness of sunscreen — the higher the SPF, the more protection a sunscreen offers against UV-B (the ultraviolet radiation that causes sunburn).

The SPF is the amount of UV radiation required to cause sunburn on skin with the sunscreen on, relative to the amount required without the sunscreen.^[8] There is a popular misconception that SPF relates to time of solar exposure. For example, many consumers believe that, if they normally get sunburn in one hour, then an SPF 15 sunscreen allows them to stay in the sun 15 hours (i.e., 15 times longer) without getting sunburn. This is not true because SPF is not directly related to time of solar exposure but to amount of solar exposure. Although solar energy amount is related to solar exposure time, there are other factors that impact the amount of solar energy, like the time of day. This is because, during early morning and late afternoon, the sun's radiation must pass through more of the Earth's atmosphere before it gets to you. In practice, the protection from a particular sunscreen depends on factors such as:

• The skin type of the user.
• The amount applied and frequency of re-application.
• Activities in which one engages (for example, swimming leads to a loss of sunscreen from the skin).
• Amount of sunscreen the skin has absorbed.

The SPF is an imperfect measure of skin damage because invisible damage and skin aging are also caused by ultraviolet type A (UVA, wavelength 320 to 400 nm), which does not cause reddening or pain. Conventional sunscreen blocks very little UVA radiation relative to the nominal SPF; broad spectrum sunscreens are designed to protect against both UVB and UVA.^[9][10][11] According to a 2004 study, UVA also causes DNA damage to cells deep within the skin, increasing the risk of malignant melanomas.^[12] Even some products labeled "broad-spectrum UVA/UVB protection" do not provide good protection against UVA rays.^[13] The best UVA protection is provided by products that contain zinc oxide, avobenzone, and ecamsule. Titanium dioxide probably gives good protection, but does not completely cover the entire UV-A spectrum, as recent research suggests that zinc oxide is superior to titanium dioxide at wavelengths between 340 and 380 nm.^[14]

Owing to consumer confusion over the real degree and duration of protection offered, labeling restrictions are in force in several countries. In the EU sunscreen labels can only go up to SPF 50+ (actually indicating a SPF of 60 or higher)^[15] while Australia's upper limit is 30+.^[16] The United States does not have mandatory, comprehensive sunscreen standards, although a draft rule has been under development since 1978. In the 2007 draft rule, Food and Drug Administration (FDA) proposed to institute the labelling of SPF 50+ for sunscreens offering more protection. This and other measures were proposed to limit unrealistic claims about the level of protection offered (such as "all day protection").^[17]

UV-B sunlight spectrum (on a summer day in the Netherlands), along with the CIE Erythemal action spectrum. The effective spectrum is the product of the former two.

The SPF can be measured by applying sunscreen to the skin of a volunteer and measuring how long it takes before sunburn occurs when exposed to an artificial sunlight source. In the US, such an in vivo test is required by the FDA. It can also be measured in vitro with the help of a specially designed spectrometer. In this case, the actual transmittance of the sunscreen is measured, along with the degradation of the product due to being exposed to sunlight. In this case, the transmittance of the sunscreen must be measured over all wavelengths in the UV-B range (290–320 nm), along with a table of how effective various wavelengths are in causing sunburn (the erythemal action spectrum) and the actual intensity spectrum of sunlight (see the figure). Such in vitro measurements agree very well with in vivo measurements.^[18] Numerous methods have been devised for evaluation of UVA and UVB protection The most reliable spectrophotochemical methods eliminate the subjective nature of grading erythema.^[19]

Mathematically, the SPF is calculated from measured data as

where E(λ) is the solar irradiance spectrum, A(λ) the erythemal action spectrum, and MPF(λ) the monochromatic protection factor, all functions of the wavelength λ. The MPF is roughly the inverse of the transmittance at a given wavelength.

The above means that the SPF is not simply the inverse of the transmittance in the UV-B region. If that were true, then applying two layers of SPF 5 sunscreen would be equivalent to SPF 25 (5 times 5). The actual combined SPF is always lower than the square of the single-layer SPF