hi there!
nitric acid is what i use for my etching projects. just be careful whan you dilute the acid.
some say that beeswax is the best but what i found to be handy in this case is a product that looks like tar but a bit in a melted condition, that most people use to cover soldered bits in order to perform further soldering! sorry, but my english terminology and vocabulary is not that good since I'm greek, but i'll look the name of the product tomorrow at work and i'll get back to u.
I do also have the book that you mentioned, it's one of the best, very technical though and at times not so explanatory as in your case(which resist for which acid). the thing that i do is try most of the things it mentions. trying stuff is the best for our job. you'ii be amazed with what you may come acrross and be suitable for you!
cheers,
Mitro