My opinion, don't waste your time with Barnbaum's book (on any topic actually). It gives no detail or methodology on masking.
I appreciate the heads-up on this. I was looking at his book on amazon last night after reading this thread and saw that his section on masking was a listed as a single page in the table of contents. It can't be very informative if he only devotes one page to cover the topic while other people use entire chapters and even volumes to cover simpler techniques than masking.