I've heard that if you use a backing board such as bce's life x-tender (which has a thin layer of charcoal between two backing boards) and put it in the middle of the comic, it helps extend the life of the comic by absorbing acids as they are released from the paper.
But, it also makes me wonder, if you put the board in the middle of the comic, do you risk damaging the spine more easily?
Up until now, I have always put the backing boards behind the comics. Makes me wonder if I should start putting them in the middle now.