That's due to the oil barrier. I like that idea, would like I'd considered it!! On the other hand, that is, I now 3D print cat food bowls that have an extremely modest, canted inward oil ring, which stops kittie's fur from accidentaly finding oily. It really works really well https://petstoredubai51358.suomiblog.com/new-step-by-step-map-for-pet-shop-dubai-51992729