i tried this many years ago -- before i was actually motivated enough to just stop coloring.
it was explained to me that my dyed color was too dark to strip, so if i used lighter colors as we went along at some point they could strip the color.

for me, it was a disaster as the colors were too light to cover the gray and they oxidized and had an orangey cast to them, not good at all for my complexion. i stopped after about 3 months, went back to my regular color. then a few years after that i just stopped coloring.

and, while the lighter shades that were used were not demipermanent, my daughter had demipermanent in her hair for her wedding to cover her grays. (like me and my dad, she started graying early, but really, not noticeably at that time, but....) well, same thing happened to her. instead of it fading out in 3 weeks as she was told, it stayed, oxidized, and two years later she cut off the last of the orange color.

so, that was my experience and my daughter's. others will have different experiences to relay.

i sure wish we had a "gray curlies" forum!!!!
[FONT="Arial Narrow"]
3a, some 2c & 3b, medium texture, porosity normal, low elasticity
washing/cowashing, conditioning, protein tx: [I] curl junkie products
leave in:cj conditioners and treatments as leave in
styling: cj aloe fix gel, cj pattern pusha, cj honey butta leave in, cj cccc, cj ciab.
sealants - jane carter nourish & shine