Straightening Color-Treated Hair
A: You should always use care when using thermal styling on color-treated hair.
The biggest concern, however, is that when the hair is color-treated, it is more susceptible to damage from heat styling appliances. Because of the increased porosity, the hair doesn't retain moisture as well as untreated hair.
Always take extra precaution to prevent heat damage by using extra-conditioners and protective products when performing any thermal styling.
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See also:
Hair straightening
Heat styling basics
How to minimize hair color fading