Paper was different once is in fact the beginning of the Introduction to Volume I. It stresses how different our experience of paper is now from that of our predecessors.
The Papermaking Process is an outline of the papermaking process that was in general use at the beginning of the 18th century. It is described under five headings, starting with the selection of raw materials, and ending with sorting, finishing and packing.
White Paper was mostly made from "rags" i.e. recycled fabrics and ropes, which meant a lot of skill was required to achieve consistency of the raw materials. Appendix V deals with Rags, and we present two sections concerned with the Flax and Linen which ultimately became paper.
The modern view of Alum is that it has no place in the manufacture of high quality papers. Yet it was used in papers which are still in excellent condition after more than 250 years. The whole of this important investigation is available here.
Appendix IV of The Elder James Whatman assembles the details of research into the people responsible for the emergence of Maidstone as a papermaking centre in the 18th century. It includes the results of searches of more than 50 Parish Registers and other documents such as leases and wills. You can find here the example of the entry on George Gill and a short list of names of papermakers extracted from the index. The full index of papermakers includes the names of more than 150 people.
Appendix V of the The Whatmans and Wove Paper is a substantial essay entitled The Genesis of Modern Drawing Paper. The list of contents and the first two sections set the scene.