How to copy old books made of cotton paper?

If this book is not particularly precious, but just a general version, you can find the end of the binding line first and open it carefully. Don't break the whole line. When the whole line is removed, you can copy or scan the book without bound lines page by page. After finishing all loose pages, arrange them neatly in order, and then re-bind them with the removed thread according to the original thread hole. However, if it is a thread-bound book of rare ancient books, I hope to start with caution, or find an experienced old binder to disassemble it. Although I can disassemble it, I really don't know what to say to make you understand and operate without pictures. Anyway, don't be careless.