I recently recieved some coins had given my Grand-parents long, long ago had forgotten about them. Were stored in dresser drawer 25 plus years and now show some rust on staple, figure light brush with steel wool should cure them. The holders have centimential value, as I dated each one and to whom coin was given..>>>>>> Your question, how long takes to rust ... can only be answered by you watching the holder for the rest of your life. Good Luck, OzarkTravler
The staples that size don't rust that fast.Unless you store your coins outside in the rain, you should be fine.