I did the hot water treatment on Pleasant Company GT 9 doll. I boiled hot water in a kettle. Poured it in a bowl or dish. I slowly dipped GT9 curled roller set hair in the water. Each time making sure that each section was receiving hot water on each strand of curled hair. Then I dipped my wire brush into the hot water, wire teeth first and brushed her bangs making sure to get it completely saturated with the hot water.
I laid her on a chair to drip dry putting a towel down underneath to catch dripping water runoff.
After her hair was completely dry, I kept the curlers in for two days.
After the two days I unraveled the curlers and what a difference! Nice shiny curls to go with her Easter best.
Materials: Foam rollers, wire brush, hot water...parent supervision if needed, 1 bowl and towel.
Note: I was careful trying not to get the top of the wig wet, but as long as you are not putting the doll head first under a running faucet, a little water will not hurt. Avoid getting water in eyes at all costs.
Hope this helps. It has really improved the quality of my GT9 doll since she is rather old.