John Farleigh, in a chapter about Sidney Cockerell from his book The Creative Craftsman, gives a particularly observant account of the relationship between a book binder and a bone folder.
“Another man is at work putting down a leather joint on the inside of a bound book, using a folder with quick, skillful movements reminiscent of the grooming of a horse. The folder, a small ivory instrument that has to the ordinary eye the appearance of a paper-knife, is in fact a most important tool to the binder. Its shape is fashioned with great care and according to the habits of the craftsman himself. Every facet of its surface, every curve and subtlety of its edge, is known and used for a purpose, and no craftsman will readily part with this tool. This particular craftsman tells us, as he would talk of the loss of his nearest and dearest friend, that he has just broken his folder—an extra thick piece of vellum needing rather more pressure than usual found a weakness in the ivory—and we are shown the sad remains”
The finest bone folders on earth are being made today by Jim Croft, pictured below. He processes wild deer and elk bones with his teeth and hands. He also offers intensive workshops on making books from raw materials: toolmaking, processing fiber, papermaking, and wooden board binding with clasps. Below he is wearing his signature bone folder vest. Check out his website, traditionalhand.com, or email him to purchase raw or finished folders: traditionalhand AT gmail.com
John Farleigh The Creative Craftsman (London: G Bell and Sons, 1950) 92.