Dear Bibliobull –
Dear Gluey –
Usually this isn’t a problem that needs fixing, but since it stands out it must be pretty obvious. Most often the cracked gutter scenario occurs when you have heavy art books or illustrated plates come away from their facing pages.
The fix is similar to tipping in a page, ‘cept you have no page to insert. And the secret to gluing paper is that “less is more”, no really it is i swear. The more you use, the more difficult you make it for yourself.
You can apply the thinnest amount of glue using an index card or basically any piece of cardstock. Put a small dollop of glue on a piece of scrap paper or card, then using a CLEAN index card run the edge of the card through a small edge of the glue puddle. Ideally there should be no rounded glue bubble on the card, just a smooth smear. If you pick up too much glue you can wipe your index card back against the scrap paper to remove some. What you want to end up with is an index card with a long shiny stripe down the edge.
Open the offending cracked section as wide as possible, and slide the index card down the gutter against the facing page. Now lay a piece of wax paper in between the two pages but not all the way into the gutter. We are talking millimeters of clearance here, so exact placement isn’t a big heavy deal, just don’t try to push the wax paper all the way into the gutter. Close the book and in the morning tug the wax paper out.