One important distinction: metal mesh grease filters are washable. Charcoal or carbon filters, which some recirculating hoods have behind the mesh, are not — they are designed to be replaced, and washing them ruins them. If you find a black cassette-like cartridge, check your model number and replace rather than soak.
Can I put the metal filter in the dishwasher?
Often yes, on a hot cycle placed upright so water can pass through the mesh, but with one caution: aluminium filters can discolour to a chalky grey in some dishwasher detergents, which is cosmetic rather than harmful but permanent. If your filter is stainless steel, or you do not mind the dulling, the dishwasher is a perfectly good shortcut. If it is new, shiny aluminium and visible in your kitchen, the sink soak is the safer choice.
How often should I actually be doing this?
For most households that cook a few times a week, once every one to two months keeps it easy; if you fry, roast or cook with a lot of oil daily, monthly is more realistic. The honest test is to hold the filter up to a window — if you cannot see daylight clearly through the mesh, it is overdue. Doing it little and often takes twenty minutes of mostly waiting, while leaving it a year turns it into a genuinely unpleasant job.
