If you don't dry your snowboard off after every use, you're bound to get some rust on the edges of your board. Tuning up your board regularly will increase your board's performance and give it a longer life. You can send your board to a shop for maintenance, or you can get rid of the rust much cheaper on your own at home.
Prevent the Rust
The first thing you should do when you buy a new snowboard is take every precaution to keep it from rusting in the first place. Dry your snowboard, especially the edges, when you come inside from the slopes, even if you're going back out in an hour or two. Don't leave your board outside in the snow, on your porch or in the racks on top of your car. All of these places are open to the elements, and if you're board is sitting in a pile of water or snow, it's going to rust.
Remove Rust with a Gummy Stone
Even with preventative measures, most boards do develop surface rust over time. When you examine the edges of your board and see rust spots starting to form, the easiest way to get rid of them is with a gummy stone or diamond stone. Rub the stone on the edges where the rust needs to be removed. Always use the stone in a tip-to-tail motion with short strokes. Be sure to do this to the base edge, as well as the side edge or wherever rust is present.
Remove Rust with Sandpaper
If you don't have access to a diamond or gummy stone, or are short on the cash to buy one, buy a couple sheets of fine and medium grit sandpaper at your local hardware store. Start with the fine grit sandpaper and rub it on the steel edges of the board. If the rust isn't deteriorating with the fine grit sandpaper, use the medium grit. Always rub the sandpaper on the rust in a tip-to-tail motion with short strokes.
Prepare Your Edges for the Offseason
As much as you hate to do it, at some point you're going to have to put your board away for the offseason. Now that you've got the rust completely removed, you need to make sure you board doesn't collect any new rust while its in storage. Dry your board completely from nose to tail. Now melt a thick coat of snowboard wax on your edges using an iron, preferably not your mom's because you will not be able to get the wax off. Don't scrape your edges until you take the board out of storage. The thick coat of wax will prevent the edges from rusting while they're not in use.