Just to add variety I suppose, the way I'm thinking is that there's a bunch of solutions purposed that would require soap. And, since I was planning on sending people to investigate various things (Effectiveness on soap water as deterrent to scare slimes, if control is possible on city based slimes, and what would happen if soap was thrown at the tide) I thought if there was another non magical way I could spice things up. I spent a lot more time more time trying to think of one than I care to admit.Why without soap? with wood ash and water, gallons of Lye water could be produced in a forest dense area pretty quickly...
Personally, I am still toying with the idea of a peaceful solution...