They are metal in an acidic environment they are going to rust. I use plastic ones for storage, https://www.amazon.com/gp/product/B07T1G5JDZ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1. They have a rubber grommet so waterproof. If you close them too tight you will never get them off though or if they form a vacuum. Fixed the rusting problem thought.