Here are some notes on a book I bound more than fifty years ago. It has never flattened out in spite of being gently squashed on bookshelves ~ with occasional use ~ for all that time. What went wrong? I failed to let it dry out properly. A craftsman should never be governed by pressure of time.
The book in question was my course work - an extended essay on a mathematical subject. As always I had left things to the last minute. A fully-bound leather covered book needs several weeks to dry out ~ under pressure. I cannot recollect how close I was to 'handing-in-time' ~ it would more likely have been hours rather than days ~ let alone weeks. There was certainly no time to rectify it. Fortunately I did better with my craftwork extended essay ~ which was also bound in red Morocco leather . (How did I afford that on a student grant?)
Here is a brief explanation of the process of binding ~ all round ~ full-binding ~ tight-back ~ in leather.
For the leather to be workable ~ and to stick well ~ it needs to be very well pasted. One of the definitions of glue is that it does not have slip ~ paste does. Slip is essential in this process. It can take an hour or so to work the tight-back and slip is required for much of that time.
Leather absorbs lots of moisture. When I last covered a book by this method I left the paste soak into the leather for half an hour ~ and replenished it once or twice during that time. To prevent drying-out the leather needs to be loosely folded over onto itself ~ and also placed in a plastic bag to prevent moisture evaporation.
The boards are pasted ~ to allow for their swelling. They also soak up lots of moist paste. To get everything done in one session the paste-down is also pasted . After the hair-rasing process of putting the cover on ~ forming the spine at head and foot ~ nipping round the cords ~ and ensuring there is no slip ~ drying can start. The water from all that paste has to evaporate. The book has to be pressed between boards. There is very little route for the vapour to escape. Pressing continues for a week ~ or two ~ or three.
In a bookbinder's workshop you will find a huge press with a dozen books slowly drying out.
The process can be hastened by careful airing from time to time. Careful because pressing will need to continue for as long as there is a trace of dampness. The airing is also necessary to prevent mould from setting in ~ bugs love moisture ~ especially starch flavoured paste.
In the situation above there was no time to attempt flattening-out procedures ~ and so I cannot report on the success or failure of that. It would have involved some re-moistening and gentle drying again.