Hair dyes natural

Hair dyes must meet a number of conditions related to their end use. Color can be assessed by colorimetry [49], The limits of precision are set by the substrate on which the measurement is performed. Studies on test subjects are difficult because of the uneven natural hair color and the background color of the scalp. Tresses are hard to prepare at a constant quality level. Measurements on wool cloth give reproducible results, but for oxidation dyes the shades are not identical to those produced on hair. Colorimetric methods are therefore useful only for comparative measurements on the same object, for example, in lightfastness tests. Because hair must be redyed after four to six weeks due to growth, the fastness required of hair dyes is generally less than that needed for textiles. However, stability is still a problem with many indo dyes (see Section 5.4.3). Some of them... 

Hair dyes are of two types permanent and semipermanent. Permanent dyeing is achieved with a synthetic dye, applied with hydrogen peroxide that first bleaches the natural pigment melanin. Semipermanent dyes are generally made with vegetable extracts, such as henna, that coat rather than penetrate the hair shaft. There are a number of questions about the safety of synthetic hair dyes, since some of the products they contain cause cancer. 

Other natural hair dyes that have been used down the centuries have been indigo (chemical name 2-[i,3-dihydro-3-oxo-2H-indol-2-ylidene]-i,2-dihydro-3H-indol-3-one) extracted from Indigofera, a plant of the pea family, and pyrogallol (chemical name 1,2,3-trihydroxybenzene) extracted from walnut shells. This last dye was banned for use in the EU in 1992-... 

Crocin or saffron extracts together with other natural pigments such as berberine, azulen, curcumin, betanin, etc have been used as a hair dye [93]. In a US Patent [94] a scalp treatment composition is described for scalp and hair health and growth containing saffron, among the other plant extracts. 

Natural organic substances from plants are the earliest known hair dyes, but of the many substances of this type that have been tried over the years, only henna and camomile are currently used to a significant commercial extent [2], The active coloring material of henna (Lawsone) is 2-hydroxy-... 

In eontrast, estimation of exposure from the use of hair care products presents a different set of eonsiderations relative to skin care products (Dressier, 1998). In partieular, the assmnptions for the calculation of percutaneous absorption for hair dyes are unique to these types of products. Factors that should be eonsidered inelude the sporadie use of the product, consequential scalp exposme to the dye material, the nature of the dye itself (permanent semipermanent), and alterations in potential bioavailability eaused by desquamation. 

When the legend was in his seventies, he refereed old-timers hockey games. He looked pretty good. His hair looked especially good — nary a hint of gray. Of course, it wasn t exactly natural. The makers of a men s hair dye product had hired the... 

Definition Extract derived from Acacia catechu Uses Natural flavoring agent in foods, pharmaceuticals medicine (astringent, control of nosebleeds and hemorrhages, externally to treat boils and ulcers) hair dyes Regulatory FDA 21CFR 172.510 FEMA GRAS... 

Definition Dried flowerheads derived from Chamomilla recutita or Chamaemelum nobile Uses Aromatic bitter, natural flavoring agent in foods, alcoholic beverages, herbal teas in medicine (antispasmodic, anti-inflammatory) hair dye... 

Machida, G. Natural products for hair dyes. Jpn. Kokai Tokkyo Koho JP 2005060293, 2005 Chem. Abstr. 2005,142, 266272. 

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