So I got into these Ovenex vintage baking pans, the ones with the cool retro starburst design, and bought a couple on eBay. I hope to use them, but one has quite a few rust spots which resist my cleaning efforts. Can I still use it for baking w/o lining it with parchment? I love that starburst pattern - subtle but stylin'. I figure that if I butter it well it's not a big deal, or is it?