Why does a bar of soap produce a great lather when it’s new, then not at all when it’s smaller?

Question

It’s supposedly the same soap through and through, all the way to the core of the bar, right? Why does it react so differently to water and being rubbed on skin when it is reduced to a sliver?

In: 718

Answer 1

I assumed soap had to have some kind of useless core, until I moved from the US to France, and was amazed to have suds to the end.