The Two-Millimetre Problem: Getting Spine Width Right When Paper Won't Sit Still
You sign off a spine at 18.4mm. The finished copies arrive nearer 20mm and your title now wraps around the edge like a bad wallpaper job. This is why spine width drifts, what printers mean by tolerance, and how small presses can specify, test and artwork a spine that survives real production without a reprint.