Pro tip: stopped relaxing my spines overnight after one cracked on a Tuesday
I was in my garage in Boise pressing a 300 page text block under two concrete blocks and left it sitting 11 hours instead of the usual 3, and when I peeled the boards apart the whole spine had gone brittle and snapped down the middle, so now I check at the 3 hour mark no matter how late it is, and honestly I think the folks who say you can press overnight are setting you up to fail, has anyone else had a spine give out like that?
I had the same thing happen with a 400 page block I left in my garage in Boise for 10 hours. The middle pages near the spine felt dry and the glue just gave out when I opened the boards. Now I press for 3 hours, then move the whole stack to a cool shelf overnight so it can settle without the heavy weight still crushing it. Splitting the time like that has saved every spine since.