Hair color removers
Q: Dr. Said, could you kindly explain to me how hair tint removers work, and are they all the same? Thank you. Molly, Charlotte, NC
A: In permanent hair tints, dye precursor intermediates (called primaries and couplers, which are by themselves colorless) are coupled and locked in place by hydrogen peroxide to produce colored dye molecules. These colored molecules can be removed by two different processes: Either by a process involving reducing agents; or by a process involving oxidizing agents.
The first process, especially effective against permanent hair color, utilizes reducing agents like sulfites or thioglycolates, which act in a manner opposite to hydrogen peroxide. As mentioned above, hydrogen peroxide locks colorless dye intermediates together to produce color. Reducing agents like sulfites unlock the color molecule (undoing what peroxide did), resulting in the loss of color.
The second process involves the use of strong oxidizers such as bleach. These oxidizing agents are strong enough to permanently change the structure of the dye molecules and therefore destroy the color.
Each of these two processes has its advantages and disadvantages. Color removal by reducing agents is generally a milder process. However it requires that the reduced (unlocked) dye molecules be completely washed out of the hair (which is not an easy task) otherwise air, which is by itself a mild oxidizing agent, would re-lock the color molecule and restore color. That is why some products appear to remove the color on day of application only to have the color come back a couple of days later.
Color removal by strong oxidation (bleaching) on the other hand is more effective because the dye molecule is damaged beyond repair. But care should be taken not to cause excess damage to the hair in the process
Needless to say that neither process for color removal is totally effective. Some hues remain in the hair to different levels after either process but these generally are not of major concern if the hair is to be colored again.
It is always crucial to follow the manufacturer’s instructions for the product being used to achieve maximum results.