That is as a result of oil barrier. I like That concept, would like I had thought of it!! However, which is, I now 3D print cat food bowls which have a really smaller, canted inward oil ring, which stops kittie's fur from accidentaly having oily. It works really well https://bestpetshopindubai24578.gynoblog.com/35378625/pet-shop-sheikh-zayed-road-fundamentals-explained