The easiest way to turn a photo book into a brick is to order one of the new photo books printed on traditional photographic paper. Most of these books are produced with uncoated photo paper that is placed in direct contact with another sheet of photo paper on the opposing page. In high humidity or in the presence of moisture, the pages will stick together forming an inseparable brick.
In my tests, two weeks at 80% relative humidity was sufficient to create a photo book brick. These conditions are relatively common in tropical climates such as Hawaii and Puerto Rico, and are present elsewhere in the U.S. at various times during the year.
At this time, manufacturers of photo papers have resisted efforts to develop ISO specifications that would prevent photo books from turning into bricks, although Fujifilm did recently put out the following warning as reported in Photo Imaging News, June 22, 2009:
According to PEN Weekly, Fujifilm recently distributed a document alerting wholesale labs and minilabs about possible sticking of pages in photobooks and design albums with prints on both sides of paper that don’t have laminating on print surface, as reported in Photo Trade Express. The document recommends laminating with film, liquid lamination, or interleaving paper in between print surfaces.
At this time, I recommend avoiding books produced with traditional photographic paper, unless you are certain these books are have been tested under high humidity condition and that they are treated to prevent the pages from sticking together.