I am about to use prepasted wall paper and I am not sure I trust it. An experienced wall paper guy says that he just uses thinned vinyl paste and ignores the "prepaste". I am inclined to go that way. There is also some stuff called activator...
I haven't put up any paper in 10 years and I remember back when my father mixed his own paste out of outmeal...am I just being distrustful of newfangled ideas?