Book Restoration - An Art Form by Paul Tronson

But what about centuries of natural wear and tear or neglect and abuse?

This is where conservation itself becomes an art form, it doesn't matter what the condition be it fire or water damage, torn or missing leaves, pages taped together, insect or rodent damage,
even pages damaged by ink as this one;
click on pictures to enlarge

This level of conservation demands a total understanding of all types of damage incurred and most importantly......how to deal with it!

Invisible mending of torn pages involves knitting the fibres back together.

Insect damage will mean matching and blending in paper fibres

Water stains (tidemarks) will need to be removed first before any other stain. Any provenance such as ink or pencil writing will need to be "fixed" to the paper or they may be lost.