Hair Color Differences
Q: Besides the lasting ability what is the difference between a semi hair color and a demi hair color?A: Semi-permanent hair color is designed as a deposit only color to deposit color primarily onto the hair without lightening it. The formula is designed using smaller color molecules which allow the color to penetrate the cuticle layer and be deposited into the hair shaft. You can use heat with semi-permanent color with no concerns about lifting the hair's natural color. Semi-permanent color usually lasts from 6-12 shampoos.
A new color retouch method has been advocated by the American Board of Hair Colorists. In color retouch services, the operators should use permanent color on the new growth of the hair, and use demi-permanent color on the previously colored hair to refresh the hair's color without further stressing or damaging the hair in the coloring process.
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See also:
Hair color and coloring
The different sorts of hair color
Does semi-permanent hair color damage hair?
What is a hair rinse? Is it like coloring?