Spirit is spirit. Salt is salt. Sounds simple because it is. You could use flour or anything else. It's your intent. If you believe it then that's cool. Whatever gets you there.
I have been involved in this 'game' for four decades and have a rough idea of what is and what isn't. You can believe this nonsense or not. I prefer not to because fourty years of being in and around some of the best mediums and healers, and sat in enough circles, development and otherwise, including a physical one to know that such things are just plain silly. All these years of teachings and communication within the Spiritualist movement.... Take it from me, stick it on ya chips or spuddies.., much better.

G