16 Questions
What are the two main pigments responsible for the various hair colors?
Phaeomelanins and eumelanin
What does the higher amount of eumelanin in the hair generally result in?
Darker hair color
What is the key intermediate that reacts to produce either eumelanin or pheomelanin?
DOPAquinone
What does DOPAquinone react with to form pheomelanin?
Cysteine
What factor contributes to the variety of colors produced in nature?
Types of pigments, amount present, and size and distribution of pigment granules
Which pigment is responsible for dark browns and blacks?
Eumelanin
What is the primary function of the hair cuticle in the uptake and performance of dyes?
To regulate the entry of materials into the hair fiber
Which layer of the hair contains most of the hair pigment?
Cortex
What is responsible for the perception of hair damage related to dyeing?
The size and shape of the dye molecule
What happens to damaged fibres in terms of absorption of dyes?
They become more porous and offer less resistance to absorption
What is responsible for the differential wearing properties of dyes?
The size and shape of the dye molecule
What increases the potential for diffusion of dyes into the hair fiber?
Alkaline pH or presence of urea
What factors determine the partition coefficient of the dye between the hair and the delivery system?
Surfactants and organic solvents
Why is it important to use a combination of organic, watermiscible solvent, and adjuvants in hair colorant formulation?
To lower raw material cost
What should be favored in developing the delivery system for a hair colorant?
The release of the dye from the system
What is a desired outcome when formulating a hair colorant in terms of partition coefficient?
Increase efficiency and ease of use
Test your knowledge on the preparation of hair coloring cream and the pigmentation of hair follicles. Understand the different natural hair colors associated with ethnicity and age.
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