Unfortunately thats the nature of salt, it's hygroscopic so it attracts water. I read a case study done by palmolive where they changed their bar soap packaging to protect it in humid climates. They were using a plastic coated wrapper, similar to freezer paper, to shield the soap from the environment. This could work for salt bars since they won't grab moisture if they arent exposed to it. If you wrap them in a breatheable paper they will just pull moisture through the wrapper and get soggy.
I have also heard of dusting MP soap with arrowroot powder before shrinkwrapping. It keeps the soap from sticking to the plastic. It could work for salt bars too, after they are cured.
They should stop sweating eventually, after they cure. They need to be kept in a dry place until then.
If they are sweating, they are not curing. I've made a ghetto curing setup that involved putting the bar of soap in a paper lunch bag, then putting that in a larger plasic bag with silica kitty litter and sealing shut. The silica litter has the advantage that after its saturated, you can bake it in the oven to dry it out and use it again.
Last edited by jujubean; 07/31/12 05:26 AM.