Rant: I chose hemp cord over linen thread for my first Coptic binding and now the spine is loose
I was binding a small journal last month, about 80 pages, and I had to pick between waxed linen thread or hemp cord for the Coptic stitch. I went with hemp because it was cheaper at $6 a spool at my local craft store here in Portland, but after two weeks of use the sections are shifting. The hemp stretched more than I expected. Has anyone else had this happen, and should I just switch back to linen for my next one?
Switching to linen won't fix anything if you keep using the same stitch and tension. Hemp getting blamed here is just wrong, because linen stretches too when it's not waxed enough or when you pull your loops tight as you go. The real issue is that you sewed 80 pages in one go, so the whole block has room to wiggle and each section slowly works the thread loose over time. Try waxing the hemp harder with beeswax and making your stitches snug but not tight, then add a bead or a knot at the head and tail so nothing can slide. Two weeks of daily use on a soft cover journal is also just a lot of wear, and even linen would show some give by then. What kind of cover and board did you use, because that changes things more than the thread does?