Depends how humid you store them but if they start to rust, it might show an indication that you have stored them in a very humid environment and chances are, your coins might get affected by the humidity at the same time.
i have coins in cardboard holders for 7+ years and they show no signs of rust just be careful how u store them so the staples dnt scratch the coins behind them
There is no one answer to your question. Variables in the equations would include humidity and temperature. I would guess that the staples in a 2X2 stored in an unconditioned garage in Florida would rust faster than a 2X2 stored in a conditioned room in the desert in Arizona.
I have coins in holders that my Grandmother gave me in the early 70's and so far, so signs of rust at all. I suggest you spend a few extra cents on good staples that don't rust. Guy~
Monel makes a staple that is nickel/copper and will not rust. Mostly for archival work, hard to find, but not much more expensive than normal stainless steel or galvanized staples. Guy~
OK, I'd buy that they won't rust - but they will corrode. They very well may be a lot better than regular staples though.
I learned this in science, doesn't matter how long their exposed to moisture, it's the oxygen supply in the surrounding enviroment. The gasses of our earth are 78% nitrogen, 21% Oxygen, and 1% other. This may sound extremely wierd, but spray the staples with Bug Spray, then rub it off with a cloth with lotion on it. My grandpa found this out.(It leaves it with a glossy protective surface) <- my dog
Kind of true but not entirely. Rust is in reality a form of Oxydation and that gas has a habit of combining with almost anything. However, there are hundreds of types of Stainless Steels out there and many higher grades deter rust for massively long periods of time. Meanwhile as to staples rusting. That made me curious. I have some medical records from when I was a kid. They are stapled together and I went an looked at them. They are approximately 60+ years old. No rust on those staples and I don't think they were made of anything special back then. Probably the rust gods realized I needed those papers so they kept the rust out. So much depends on where the staples are kept, what they are made of, the invironment, what they are used for, etc. Now if made in China they are probably Lead so no problem. Ever see toys from China with rust?