Just wondering...can anybody give me advice on demi permanent hair color?
I've read that it lasts 28 shampoos or so which would require reapplication about as often as I redo my permanent hair color as I shampoo every day.
My hair is probably 35 to 40% gray, maybe more.

I'd like to grow it out to see how it would look if I went au naturel. I work in a corporate environment where "oldies" are aged out so if it turns out to be so gray that it makes me look "old" I'd keep coloring.
But I'm hoping that by using a demi permanent color, I could grow out and cut off the permanent color so I'd have my real hair, covered by a temporary color that washes away every 28 days or so. Then, if I could time it to a vacation, I could test out how I like my real hair.
Am I properly understanding how this works? (My sister let her gray grow out and loves it but she works in nursing where gray hair isn't an issue.)
Any advice would be greatly appreciated!
Thanks,
Cathy