
I think this turned out rather well.
They put me in the chair, tied the protective coverings over me, poured heaps of glop on my hair, said "Good luck," and went away for 20 minutes. Oh yes, and I was also instructed to let them know when it got to be "too much."
I waited. 20 mins later the hairdresser came back and asked how it was. "Fine."
"Can you stand another 15 minutes?"
"Sure."
Off she went. 15 mins later the process was done and hairdresser continued to marvel that I hadn't squawked. I had to keep assuring her that it really didn't hurt. :-) Scalp sensitivity - no sense, no feeling?