I'm binding a sketch book as a birthday present. This is my first experience in book-binding. I've bought 16 A4 sheets of 160g/m2 black paper and I wonder how big should be one signature of sheets. I was planning to bind four pages in one, so the book will consist of 4 signatures of 4 sheets each, but they may be too thick to be folded after binding in such bundles. So should I do 8 signatures of 2 sheets instead? Or maybe I just have to fold or bind them a bit differently?