How long do I wait after using a 28 shampoo, semi-permanent color(copper-blond) before I try henna?

No need to wait...."You can safely apply body art quality henna dyed, bleached, and chemically treated hair. You can apply synthetic dyes, bleaches and treatments over body art quality henna. "There is an excellent free ebook in pdf on henna for hair.

This is the link:hennaforhair.com/freebooks/hennaforhair.

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