It gives bars nice slip and shine.
Kaolin may whiten the base slightly, however, it will give more subtle white look, sort of creamy. I use it together with TD. It will crackle sometimes just as TD does, sadly.
I also use pink, olive, yellow and bentonite. I like the natural colours it gives to the soap.
I sort of didn't believe in all the promises about how it will do this or that to the skin. But I have to say, it does something funky and my skin feels cleaner but softer and less dry at the same time.
I love it!