Semipermanent hair colorants

Semipermanent hair color products are formulated at an alkaline pH, usually between 8.5 and 10. At this pH the cuticle of the hair lifts away from the hair a Httie, allowing for easier penetration of dye. An alkyl amine buffered with an organic acid normally is used to obtain the desired pH. The formulations contain a mixture of solvents and surfactants to solubilize the dyes and a thickening agent is added so that the product stays on the hair without mnning or dripping. A 20—30 min appHcation time is normal for this type of product. A representative formula for a semipermanent dye product is given in Table 7. 

Semipermanent hair color products have the advantage of being removable if a consumer is not satisfied with the result, the color is gradually washed out of the hair. The products are perceived as very gentie. The ease of removal of these products is also a disadvantage because a consumer needs to reapply the color after every 6—8 shampoos to maintain the color. 

Also present but not essential in permanent hair colorants are nitro dyes which dye hair without oxidation. These dyes, nitro derivatives of aminophenols and benzenediamines, impart yellow, orange, or red tones. Although they have good tinctorial value, they are not as colorfast as the oxidative dyes. They also are used in semipermanent hair colorants. 

Permanent hair colors contain an oxidizer (usually 6% hydrogen peroxide) and a dye intermediate (p-phenylenediamine, resorcinol, aminophenols along with water, ammonia, glycerin, isopropanol, and propylene glycol). Semipermanent hair colors contain propylene glycol, isopropanol, fatty acids, fragrance, alkanolamines, and dyes. Some Grecian hair formulations contain lead in the form of lead acetate. 

Several recent scientific studies have been concerned with the application of high-performance liquid chromatography for the analysis of direct dyes in semipermanent hair coloring products primarily for quality control purposes [37, 42]. This technique has been used successfully for the complete separation of 18 dyes in a standard mixture and also for the separation and analysis of these dyes in eight commercial hair color products. 

Permanent hair colorants, frequently identified as oxidation dyes, show much greater resistance to fading and shampoo loss than do semipermanent hair colorants. As a rule, these dyes remain on the hair it is common practice to dye only that portion of the hair... 

Uses Surfactant for semipermanent hair color systems Lowenol 1985A [Lowenstein Dyes Cosmetics]... 

Zonyl 8867L Zonyl FSG Zonyl FSH surfactant, waxes textile dyeing/ printing Uniperol EL surfactant, WBM Chemid CDM-211 Chemid ODA-100 surfactant, weak cationic semipermanent hair colorants Lowenol T-163... 

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