Just realized I was pressing my signatures too flat after 6 years of sewing them
I used to bone down every signature until the fold felt like a knife edge, thinking that was the whole point. Last month I was rebinding a beat up copy of a 1974 paperback for a friend in Bellingham and the spine cracked right along my crease at the second section. A guy at the bindery supply counter told me to ease off and leave a little roll in the fold so the paper has somewhere to go when the book opens. Now I press gently with the flat of my hand and only bone the very ends, and my last 4 books all open flat with no cracking. Anyone else go through a phase of overworking the fold like this?