Study Set Content:
¨ Hair-coloring products fall into two general categories:
(1) those that are based on materials that are inherently ().
(2) those that use colorless precursors and develop their hair coloring characteristics only on interaction with an ()
Colored, oxidant
Dyes of the first category are used in ()(or shampooremovable) products and semipermanent color formulations (color stable to several shampooings).
temporary
The second category forms the mainstay of so-called () hair colors.
permanent or oxidative
Their importance lies not only in the durability of the effect, but also in that the natural ()of hair can be modified, almost at will, to any desirable hue or shade, whether darker or lighter than the original.
color
¨ This is accomplished in one step through a combination of () of the natural pigment present in the hair and simultaneous color development.
¨ Such shade manipulation is clearly not available in the temporary or semipermanent products, the function of which is primarily restricted to the buildup of color ().
bleaching, intensity
Although semipermanent colorants lack the versatility of oxidative dyes, they are recognized as being gentler to hair because no() is required.
peroxide
¨ In each hair-coloring category, a () number of dyes (or precursors) is required to attain a viable palette of shades.
¨ These dyes differ not only in their() characteristics, but also in their affinity to hair, water solubility, and overall photostability.
sizeable, chromophoric
In color impartation, a delicate balance of constituent dyes is essential to obtain uniform and desirable results. However, subsequent exposure of dyed hair to shampooing, sunlight, perspiration, and simple wear and tear often highlights the differences in properties of dyes that can result in () color changes.
unpredictable
As the name itself implies, the dyes of this class are scheduled for only a fleeting residence on hair being removed at the first shampoo opportunity.
Temporary Hair Colorants
Although the postulate of fast removing precludes the use of()colorants that could penetrate the hair shaft, it nevertheless extends the palette to almost any toxicologically acceptable dye that can be aesthetically formulated into a cosmetic vehicle
low– molecular weight
¨ In general, food colors, cosmetic colors, pigments, or even textile dyes can be considered. ¨ To be avoided are strongly() dyes that have a tendency toward intensive skin staining and a high affinity for chemically damaged and weathered hair
basic
FD&C Blue No.1
Triphenyl methane
D&C Red No.22
Xanthene
Ext. D&C Yellow No.7
Nitro
D&C Brown No.1
Disazo
D&C Green No.5
Antraquinone
D%C Red No. 33
Azo
This class of dyes, initially designed exclusively for gray-hair coverage, has progressively grown in importance as the formulation changes extended the color palette and improved the durability of the imparted color.
Semipermanent Hair Colorants
The majority of products features a blend of()– molecular weight dyes that are capable of penetrating into the hair shaft, thus assuring a moderate degree of fastness
low–and medium
A () is necessary to achieve the desired color and obtain a match between the roots and the more permeable ends.
blend
