Depending on the hair you are using…after a while, with all the dipping in hot water, the ends will start to look trashy and ashy…I usually don’t keep them in for longer than three weeks after I start dipping.
There is a way to get your ends straight OR curly without using hot water…
for the curly method: if you are wearing braids that are loose at the ends, just blow them straight with a hand-held dryer (the braid hair can be dry or damp, doesn’t matter) —the blowing will make the hair super-straight, then you can braid them up, leave them over-night, undo them in the morning and you will have wavy braids. You can do this over and over for several weeks. The hair wont get trashy like it does with hot water over time…when you undo the braids, just add a little light oil to give it some sheen.
Now, to get the hair straight, all you have to do is use a blow-dryer once again with a comb attachment and blow the hair on the highest setting. it will become super-straight, without the use of hot water. You can do this over and over for several weeks.
Credit to: http://forum.blackhairmedia.com/dipping-your-ends-in-hot-water_topic113254_page1.html