Additives: The Small Ingredients That Do Big Work: Rheology Modifiers, Dispersants, Wetting & Leveling Agents, Defoamers, Driers, and Corrosion Inhibitors (Paint Formulation for Beginners)

This book covers six additive categories, chosen because they're the ones you'll run into constantly, no matter what kind of coating you end up formulating:
Rheology modifiers — control how the coating flows, from the can to the wall (or panel, or pipe) and everywhere in between.
Dispersants and wetting agents — get pigment particles properly separated and keep them that way.
Wetting and leveling agents — get the coating to stick to the substrate on contact, then smooth out into a uniform film once it's there.
Defoamers — manage the air that gets whipped into a coating during manufacturing and application.
Driers — speed up the oxidative cure of alkyd and oil-based systems from days to hours.
Corrosion inhibitors — slow down the electrochemical process that turns coated steel back into rust.
Book 1's Chapter 1 additive overview touched on all of these at a high level. This book gives each one its full due.
There are other additive categories in the wider world — biocides and mildewcides, coalescing aids, matting agents, UV stabilizers, slip agents, and more — that aren't in this book. That's not because they don't matter; it's because a book that tried to cover every additive category with equal depth would be a reference manual, not something you'd actually read. These six show up on the most formula sheets, cause the most first-year confusion, and do the most damage when they're wrong.