De-greying a head help.

[noelani72]

I bought a zombie-fied Torch off a great member here with hopes of de-zombiefying the head.
I followed the tutorial in CustomMego:

http://megomuseum.com/custom/degreying.shtml

and after 12 hours, I peeled the plastidip off and there was zero change, well, there was change - it managed to pull some of the yellow paint off the head.

Does the plastidip trick only work on flesh tone heads or would a Torch head just need more time, more dips?