So you have left your barbecue out in the rain all winter and now you want to know how to clean rusty grill grates? The method you use to clean your grill grates will depend on what material they are made of. Typically barbecue grills grates are made of stainless steal or another type of metal. Most people clean their grill after each use with a stiff wire brush. This can be effective in removing the rust off of most grates, but could harm the finish of a stainless steel grill. Below are several methods of cleaning rust from grill grates. You may want to use the gentlest method first, and work your way down the list until the rust is gone.