I am disappointed with this product. I have owned 4 of these muffin pans for a few years. I use them maybe 10 times a year. I never put them in the dishwasher and always hand wash mine. However, the bottoms of all 4 pans are covered in rust and there's a good amount of rust on the inside of the muffin holders. This is a good brand with a good reputation and expensive products, but these muffin tins do not reflect that. The only reason why I didn't give it a 1 star is because they are very heavy and do not warp.