As the main goal, never ever replace rare book's original handmade headband with a new one, it is one of the most important historical evidence which carries a lot of codicology information. However, conserving this headband - if necessary - is the optimum choice.
What does Headband (Endband) mean?
Headbands are one of the bookbinding characteristics, especially most often found with hardcovers. The headband (or in sometimes called Endband) made up of a small cord or strip acting as a support of material affixed near the spine to provide structural reinforcement and sometimes decorative effect.
The most common physical deteriorating effect is readers common to pull a book out by hooking their finger over the top edge of the book spine, which create a physical force to the headband resulting after hundreds of this action a severe damage. Rather than other chemical deterioration factors representing headband material acidity.
Here is a video demonstrate unusual way to conserve and restore headband;