This is written from a fuser's point-of-view but I think lots of the information would be interesting to lampworkers who like etching beads. The author, Paul Tarlow, spends lots of time talking about abrasives that work on glass and grit theory. It's a thin book with large print but I found the book very useful since it pulled together lots of the bits and pieces I've seen about coldworking into one place. Anyway I highly recommend it for anyone who is interested in fusing and for any lampworker who is interested in coldworking their beads to change the surface quality.
I got it direct from the author
http://fusedglass.org/ I wasn't impressed with their shipping. It's also available from Brad Walker's site
http://www.warmglass.org/servlet/StoreFront I ordered Brad's updated book and The Joy of Coldworking on separate occasions and both times the books shipped very quickly. So I'd recommend the Warmglass site if you're interested in ordering the book.
BTW The Joy of Coldworking is also excellent but it is about using various machines to change the glass after it has emerged from the kiln. Even one of the machines is an expensive investment. But if you've ever wondered about saws, laps, sandblasters, etc, this book details it all. The Tarlow book is about using various grit slurries and diamond handpads to create changes in the glass surfaces.