Well I relax a friend's hair of mine, who is only SL but uses a whole tub of relaxer for each touchup. It is the ORS extra strength one we use, and there was barely enough for her hairline (I do that last and start at the crown). I always wash it out when she tells me that it starts to tingle, because I really do not want to burn her. However, it does not take as well as I want it to, she is slightly underprocessed, even with a LOT of smoothing. By the time I finish the whole head, the relaxer has been on the crown about 20-25 minutes.erplexed ( and I do work quickly). I would rather her be underprocessed than burned. So thick haired relaxers, how do you do it?