Bleach bathing is another approach to the Bleaching process. It is a perfect step by step process that is not as strong, so it is not as damaging as the full strength Bleaching process. It is ideal to use to remove Colour, one shade at a time, or Lighten your Hair in a gentler process.
Bleach baths are great for people with skin problems (e.g. Keratosis Pilaris). A friend of mine and I both have it. She started bleach baths and hers is now gone/under control. I will be trying it soon :) I will edit this post once I have tried it to give my results.