What is "Foxing"

[uffda51]

I thought it had something to do with Nellie Fox and the 1959 Go-Go White Sox . . .


"I wondered why the baseball was getting bigger. Then it hit me… "

[brob28]

Any chance anyone has a picture they can share showing this? Trying to get a visual of foxing vs. toning. Would love to see a before and after of any cards that have been treated by a conservator.

Thanks,