Interesting that you bring up TiO2, because I noticed the latest labels of Ivory soap, which they are labeling the ingredients of (which I find interesting in itself, because for many years after the ing. labeling requirement for cosmetics was passed, they didn't), don't mention it. That wouldn't mean much except for the fact that a short while ago, when I noticed they'd started listing ings., it was listed. But that may have been before P&G sold their Ivorydale facility to someone else who they now buy the soap from. I have a hunch that whoever's making their soap now is using fats that are in better condition than P&G was last using and so have less need of whitening. Ivory being whipped/air infused (to float), it wouldn't need TiO2 for opacity, just to overcome yellowness, and I had been disappointed to learn that they were using TiO2 because of what that said about the fats they used, and I don't think they used to years ago.
As for TiO2 enhancing colors, I can only imagine it's acting as a lake. Some colorants will benefit from that, others won't.
