Unfortunately, Tin bands RUST.  All Tin bands do it.  Ours, Ball, Kerr ... it happens to ALL of them.  They are just not made to last forever.  Anytime Tin comes in contact with water, the potential of rusting WILL happen.  The best way to extend the life of your bands is to keep the water off of them and as quickly as possible.  Wash your bands with warm soapy water, rinse and dry IMMEDIATELY! Do not allow them to air dry on a towel on your countertop.  And absolutely NO DISHWASHER EVER!I have also been told that a little lemon essential oil and baking soda does the trick as well.MBC is NOT responsible for rusting on bands and or transfer to glass.  I will always suggest for  you to upgrade your bands to a Stainless Steel (Rust Proof) band to keep your glass (and sanity) rust free.  They come in a variety of colors as well :)  Extra Bands & Stainless Steel bands found here:https://themasonbarcompany.com/collections/extra-bandsI hope this helps.  Please let me know if you have any questions!