Technical Currency Expert Help needed

Anyone know who the technical resident expert on currency is? I have a few technical questions. Thanks.

 

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Feel free to ask in this thread. There are a lot of folks with great specialized knowledge here.

 

what cause rust on a stack of currency notes that have been kept in is boxes in a dehumidifed environment

 

Probably not rust , probably a thing known as Foxing on the notes . From PMG website .....,

FoxingFoxing describes small spots or discoloration stains on a note, often caused by mold or fungal growth on paper. It may also be cause by natural paper oxidation.