There's one very important, fundamental rule, that must be followed when creating layers of soap and that is to spritz the cooled layer with isopropyl alcohol before pouring the next layer. If you don't, chances are the layers are going to fall apart when the loaf gets cut. I know -- I've had this happen to me.
In light of that fact, wouldn't you think I'd never forget to spritz again? That's what I would think. I haven't actually forgotten again, but I've come close several times! I fear it's just a matter of time.
Have you ever forgotten to spritz between layers? What was your outcome?