Most comic books become damaged due to user error, either by spilling something on it, bending it the wrong way, or even with improper storage. Other times, a comic book can become damaged even with proper storage through natural disasters, accidents around home, or even by little critters that like to eat paper. There are many ways for your comic book to become damaged and this can be a sad thing for a passionate comic book collector. Enter the concept of comic book restoration.
Restoration is the process of fixing the kinds of above mentioned issues. This process is used to improve the grade, or condition, of the comic book. Cleaning is usually a part of this process, but that only relates to taking away the dirt and grime of an old comic book. Restoration often goes beyond that in using techniques to fix misshapen pages and also in adding new material to a comic book to fix damage such as tears, fading, or stains.
Comic book conservationists can actually repair quite a lot of the damaged comic book. They can take repair missing parts of the page in a variety of ways. One way is through the process called leaf casting which is a complex process where paper pulp is reintroduced to the page to fill in those holes and missing parts of the page. They can also fix bent and wrinkled pages to make them look very much like new. Conservationists can also recolor covers and pages, doing so by hand with acrylic paints, to match the existing artwork and make it look like the original.
Be warned though, the restoration process can be very expensive and should only be done by qualified experts on those vintage comic books. The restoration process can actually cost more than a comic book is worth if you are not careful, though one might not care if their goal is to just have a great looking comic that truly means a lot to them.