Interesting project, did not realize bookbinding remains popular. You have, of course, chosen a terrific book to rehab.
Is bookbinding popular with very old books, and if so does it alter the current value? (of course I realize there is intrinsic value with older artifacts in unaltered state)
There's bookbinding and there's bookbinding. What I'm doing in this case is making a pretty outside case for a poorly made book. The paper has already begun to yellow a bit, and it's a glued spine, so there's only so much I can do. This kind of design binding doesn't hurt the value of the book because it doesn't have any value to begin with, in fact it makes it more valuable 'cause now it's purty.
For older books, it depends. If you have an original Charles Darwin travel journal in his own handwriting, with all kinds of dirt like blue-footed booby poop and Galapagos turtle slobber, torn and stained, you might not want to touch it. I'd make a clamshell box to protect it, and it might be possible to mend some torn pages if they are not historically significant, so the pieces don't get lost.
For most books, there's repair, restoration, and conservation. Repair is a simple job like reattaching a loose cover, mending a torn page, etc. Restoration is more involved: I might make a new leather spine for a book that has lost its own, take a book apart and resew it, replace missing elements...the key to restoration is to keep as much of the old book as possible. For example, I will keep the old leather cover boards, even if they are damaged, and put new leather underneath old leather instead of on top of it. Say the leather spine is present, just detached. If I reback the book in leather (put on a new leather spine) and lay the new leather underneath the old leather on the cover, then put the old spine piece back on top, then only a little bit of the new leather will show. The idea is to retain as much of the character of the original book as possible.
Conservation can be more and less involved. In some cases, all you want to do is make sure a book is treated to halt any degradation - maybe deacidify the pages - and then put it in a protective box. Or it can mean disbinding, washing the pages, mending them, sewing them back together, and then putting the book back into its repaired original cover or making a new cover. You have to see what the book needs. Sometimes the old covers are really damaged and it's better to just make new ones, hopefully replicating at least the aesthetic of the old binding.
A simple design rebinding like this Alex project is sky's the limit. You can change the endpapers, add pages, make a decorated binding, anything that suits your taste and skill. I have more fun with those than with the restoration projects. With a design binding, when you're done you have something to admire. With a good restoration project, people look at it and say what did you do? I don't see anything.
