Before I worked at BTD, I had never heard of a headband. Have you? Take out one of your lovelier hardbound books and look at the top of the spine. See that little strip of cloth that's between the signature pages and the spine itself? It's called the headband. It helps attach the edges of the folded paper to the spine, and keeps your book spine from cracking and the pages spilling out. There are even sample books that show you different headbands you can specify when you're designing a book, like these from
Talas:
I recently received a fascinating catalog of books about bookmaking from
Oak Knoll Press/Oak Knoll Books, and even though I knew about headbands, I was surprised to find an entire book devoted to them, titled
Headbands: How to Work Them, and they're not talking about Pat Benatar or Jane Fonda, Bjorn Borg or Olivia Newton John.
Further googling about headbands yields some really interesting book conservation materials...worth a look!