I've seen other posts where people say different soap batches won't bond well unless they are both really fresh (in initial stages of saponification). Mine were two days apart, after most saponification was complete in the clay layer, so I'm not counting my chickens yet. The soap as a whole is still pretty soft, but tonight I purposefully put pressure on two thin end pieces to see where they would break. One bar broke almost wholly within the white part of the bar (which was the softest part), above the mountains. The other bar broke at a fairly straight angle through both parts of the soap, although one small section of it did follow the mountainside. So it seems like it would hold together under normal use. That is, if you don't drop the soap! Let's hope the clay helps with traction!
And speaking of the clay, it will probably dry & shrink differently than the white portion of the soap. This could weaken the bond. I previously made another two layer soap that had spirulina powder in half and no additives in the other half. With curing, it is smaller on the spirulina side. It has stayed together fine, but I poured both sides within a half hour of eachother so that was in its favor.
My advice to anyone wanting to work with two layers like this is to pour the second layer as quickly as possible -- which means right after your first layer has firmed up enough to do/be whatever you need it to do/be. In my case, the clay layer needed to be firm enough that I could unmold and carve it. It might have been firm enough after just one day, but I had other obligations so it ended up being ~48 hours before I could get back to it.
Remember the elephant soap I made? I carved the layers in that one while the soap was still in the mold but solid enough to hold its shape after excess batter was removed. Like 15 minutes after pouring. It is a pain to work inside the mold like that, but it's really the way to go if you can make that work. It wasn't an option with the mountain soap because I planned it as a solid bar. It didn't occur to me until much later that I wanted something different.
They look good! I hope they don't fall apart!
