Upper: hair with henna
Lower: hair 6 weeks past dye
details below

I am 70-something.  I have dyed my hair all my life, sometimes, blonde, and sometimes red, always with commercial dye.  It is presently completely gray.  I don't much like the gray hair, but I don't want to use commercial dyes again.

This is a test of my hair harvested 6 weeks after the last synthetic dye.  I had previously used Redken color gels 7NW Chestnut. The hair was tested with Jamila henna, mixed with lemon juice and Tea Tree EO.  The hair was left in henna paste for for 4 hours. 

The hair came out a little brittle from the reaction with the synthetic dye,  but is a beautiful strawberry blonde!