There are a lot of posts here on that subject. I think I even posted a tutorial and recipe on how to make salt bars. Do a search for it in the archives.
A salt bar is mainly coconut oil, and a few other high conditioning oils....mainly shea since it has a lot of unsaponifiable value, and castor to help add lather. It is not really 1 cup per pound of oils, not at all. Most soapers use 75 to 100% salt per pound of oils used in the recipe. Most of the time, since a large portion of the oils used is coconut oil, which can be drying over 30%, we take a bigger lye discount. Lots of info and like I say do the search and you'll be reading all night.
That is it in a nut shell. A salt bar doesn't produce big bubbles, as salt kills that action, hence a lot of CO is used. Read, read, read, lots of info on making challenging salt bars.
Paul :wink: