Finishing wood surfaces can be tricky and time-consuming, and all that effort and time may not yield the beautiful product envisioned at the start. Great Wood Finishes is written by an expert in the field to help the occasional finisher/refinisher or hobbyist woodworker avoid that problem. The book uses simple instructions and a wealth of illustrations to make the process easy and rewarding. Great Wood Finishes begins with a thorough discussion of tools and materials. It moves on to instructions and photo essays covering every technique, including staining, glazing, and rubbing out. The final section, primarily photos and captions, covers specialty finishes that can easily be created by combining the techniques presented earlier in the book.
It covers a lot of the same material as Flexner's book, but with more detail in some areas and less in others. It really differs in the last section where there is a picture driven tutorial to a lot of different finishes. I'd buy it for that.
If I had to say buy this book or buy Flexner's book, I'd say buy both. Older editions should be fine and they'll save you a few bucks.