'72 Topps w/ Yellow Back?

[JustinD]

I would have to dig in the archives to look for any registration back errors other than the common black. You have a point, but I have seen many wrong colors over the years although I do not have a perfect response for it off the top of the lid.

I have many wrong or missing color backs if I dig deep enough after 40 years of looking for this type of stuff. I'll try to remember this weekend to see if a registration issue is in there. I do not think this is a fading issue as mentioned prior. Perhaps, one of our printing experts can best describe the process used for back printing. As the orange is not a natural pure color for the printing process, could this be a byproduct of mixing the inks being affected by a low color if these are a single pass?

Here's a 64' wrong color that exhibits a similar yellow vs deep orange-