Book spine is the space between front cover to back cover. In common, the page count is more than 48 pages. The book spine looks better. Some customers do the book with 28 pages or 32 pages and they also like doing perfect binding with spine. In this case, we recommend the interior paper is 200gsm matte art paper or 200gsm gloss art paper. Then the book spine is around 3mm thickness.
On the book spine, it is showing book title, author name and publisher name. If the book spine space is less, we don’t recommend you put more information on the spine.
The perfect binding book spine and hardcover binding book spine are a little different. The perfect binding book spine is the interior book thickness. The hardcover book spine is the interior book thickness plus two sheets of board thickness.