Final answer:
Hair dyes lift natural pigment and deposit artificial pigment in a single process. This allows for a change in the hair color. The coloring molecule interacts with the hair's natural pigment, lightening it and allowing the artificial pigment to replace the original color.
Step-by-step explanation:
The question refers to the process performed by hair dyes. Hair dyes work in two primary ways: they lift the hair's natural pigment (usually melanin) and then deposit artificial pigment in a single process. This allows for a controlled and desired change in the hair color. The process begins with an alkalizing agent that causes the scales on the hair shaft to open up so that the coloring molecule can get inside the hair shaft. Once inside, these molecules interact with the hair's natural pigment, lightening it and allowing the desired artificial pigment to be deposited and essentially replace the original color. The molecules are generally too large to escape through the scales of the hair, so the color is locked inside - making the change in hair color permanent until new growth emerges.
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