This is one of the books that I’ve been carrying around almost since it was published in 1989, because it is so simply written and useful.  It moves from the origins of sculpture through exhibition preparation and careers in sculpture with the how-to in between. Just one of the useful chapters in this book is chapter 4 on molds.  He explains the types of molds, the design of molds, and the concepts and terminology that are needed in mold making. Other chapters contain how-to on casting and more.  The language is straight forward and understandable and the diagrams are among the best seen anywhere.  I recommend it. Buy it only for the mold making chapter and you’ll win, but it has so much more that makes it worth the purchase.
Davis Publications, Inc. Worcester, Massachusetts, USA

one of the diagrams shown in Williams "Sculpture"

This diagram shows a hard mold material being pulled from a hard cast material.