For the past two-plus weeks I’ve been baking cookies. During that time my non-stick cookie sheets have been getting dirtier. One sheet wasn’t that clean to start with. I had coated it in oil and then only used one corner for baking. As is obvious from the photo, any oil that wasn’t absorbed by the food I was cooking was instead baked onto my cookie sheet.
This was frustrating because, while it was still very slick and smooth when cold, it became just slightly tacky when heated. This made it much more difficult to remove the cookies from that sheet.
The next morning when I removed the cookie sheet it didn’t look any different. The baked oil hadn’t magically sloughed off. It had loosened, however, and with a little elbow grease and a plastic-bristled scrubber, I was able to get my cookie sheet looking much cleaner. Clean enough, to be sure.