Every Reference Guide covers one narrow technical process completely — the variables, the safety, the failure modes, and the details you'd otherwise have to find out by ruining material. There's no sequence, no prerequisite, and nothing that has to be completed. You buy the guide for the thing you're doing.

How the series works:

• One process per guide. Ammonia fuming is one guide. Ebonizing with iron acetate is another. They share chemistry but not method, safety, or failure modes — so they're never bundled into a single overview that covers neither properly.
• Complete, not introductory. Each guide is built to the same standard as the full courses. Shorter and more direct, because the subject is narrower — not because less went into it.
• Bought one at a time, at $29. No enrolment, no programme, no path. Buy the one you need, when you need it, and nothing else.

A guide is a working reference, hosted and kept current from a single source. Tables, ratios and checklists sit in the lesson they belong to, so you're reading them in context rather than hunting an appendix — and when a detail changes, your copy changes with it. Built to be opened again at the bench, not watched once.