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Just realized my last 3 case bindings all failed the same way, and it was the spine glue, not my sewing
I was rebinding a water damaged 1930s atlas for a guy in Portland last month and the text block cracked clean off the spine board on the very first open. Turned out I was using too thick a layer of PVA and it dried rock hard instead of staying a bit flexible. Anyone here switched to a mix for large books, and what ratio do you use?
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the_david1mo ago
Learned this the hard way too, and it took me way longer than it should have to see the pattern. Same thing happens with caulk around a bathtub, if you lay it on too thick it cracks instead of flexing, and thin coats always hold up better. I mix my PVA about 70/30 with methyl cellulose now for anything over 400 pages, and I add it in two thin coats instead of one fat one. The spine needs to move a little when the book opens, that's the whole point of a hollow back. Also worth checking if your PVA is old, because stuff that sat in the jar too long gets brittle even at the right thickness.
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