I finally stopped rounding my spine signatures and the old guy at Powell's bindery in Portland was right
Everyone in my local guild keeps saying rounding and backing is optional on small journals, but a guy named Dale at the Powell's bindery told me last Tuesday that skipping the round makes the text block push against the spine lining within a year. I did 12 journals his way and 12 the flat way, and all the flat ones are already showing a gap at the hinge after 6 months. So I'll say it: round your spines even on small books, the shortcut isn't worth it. Has anyone else had a flat spine fail on them like this?
Man, I've gone the other way on this one. I've made plenty of flat journals and haven't seen the hinge gap yet, but maybe I just don't beat them up enough to notice. Sounds like your test was fair though, so I'll keep an eye on mine.