The first thing I did was begin with dry cleaning the donor back cover. While sourcing a donor comic took patience and time, the cleaning of it was one of the quickest and easiest jobs I've done to date. Since the Canadian editions lack any printed ads on the cover wrap we are left with a solid blank white page to work with.

Yellow discolouration from age and foxing is present, but I will not be attempting to correct such defects (as they would require a wet bath to properly remove), I simply gave it a basic dry cleaning: First wiping it down with standard makeup cotton rounds, then since I would not have to worry about damaging ink I used a few large pieces of soft magic eraser (Mr Clean Magic Erasers are excellent. Make sure it has no scent and is fragrance-free) which works wonders on white areas of a book (these can still be used on color ink areas but require a much lighter and limited touch that I could utilize on these blank covers). 

Much of the dirt was accumulated around raised creases which I shall press out at a later date (and following the press I will do another round of dry cleaning to see if I can get some of the dirt that was inside some of these creases and could now be better cleaned with everything being flattened out).

While this isn't the most exciting or dramatic before/after example, the large amount of removed dirt left behind on my supplies made it clear it was very beneficial.