Huh, I never knew that Alzi. I just Googled and found this e-mail someone sent and got a response back.
"Dear Helen:
Thank you for your inquiry regarding Reynolds® Foil Baking Cups.
Reynolds Foil Baking Cups are packed with paper separators to prevent the foil cups from fusing together during manufacturing. These paper separators should be removed before filling the foil baking cups with batter.
Reynolds Foil Baking Cups are strong enough to be placed directly on a cookie sheet without the need for a muffin pan. We recommend placing the foil cups on a cookie sheet and filling each cup 2/3 full. To make this as easy as possible, pour cake batter from a measuring cup with a spout or drop batter from a 1/4 cup measure or ice cream scoop.
Am I the only person who just sprays the muffin pan with cooking spray and bakes them without liners? I've never made muffins with liners. I only use them for cupcakes that I have to take somewhere.