Grease filters should be cleaned once a month. This is to ensure optimal extraction. Boretti recommends cleaning grease filters with non-corrosive cleaning agents. Stainless steel grease filters are dishwasher-safe. Aluminium or metal grease filters, on the other hand, are not. When cleaning aluminium or metal, the colour may eventually take on a white glow.
Tips for cleaning by hand:
Use a special cleaner specifically for cleaning extractor hood filters or else undiluted dish soap;
Coat the filter with detergent and let it soak for a few minutes;
Then clean the filter using a dishwashing brush and hot water.