The metal filter on a cooker hood collects everything the extractor pulls up: airborne fat, steam, and the occasional flick of oil from a hot pan. Left too long, it stops filtering and starts recirculating grease straight back into the kitchen air. Learning how to clean cooker hood filter grates properly, and knowing when to replace rather than clean, keeps the extractor working the way it was designed to.
Quick answer
To clean a cooker hood filter, remove it from the extractor, submerge it in a sink of near-boiling water with two tablespoons of bicarbonate of soda and a squirt of degreaser, and leave for thirty minutes. Scrub with a soft brush, rinse and dry fully before refitting. Carbon filters cannot be washed — they must be replaced.
Grease filters vs carbon filters
Every extractor hood has at least one metal grease filter — a shiny mesh cassette that catches airborne fat. Recirculating hoods also have a carbon filter behind the grease filter that absorbs cooking smells before returning the air to the room. The two need completely different treatment. Grease filters can be washed again and again for years. Carbon filters are single-use and need replacing roughly every three to six months in a family kitchen. Trying to wash a carbon filter destroys it.
Read also: How to clean an extractor fan
What you’ll need
- Rubber gloves
- Bicarbonate of soda
- Washing-up liquid — Ecover or Method
- An optional degreaser such as Astonish Kitchen Cleaner
- A soft brush or old toothbrush
- A large sink or a washing-up bowl
- A kettle of freshly boiled water
- An old towel
Step-by-step: boiling-water soak method
- Turn the extractor off at the switch.
- Slide the grease filter down and out. Most cassettes have a small spring-loaded catch — press it and the filter drops into your hand.
- Lay the filter in a large sink, cover with two tablespoons of bicarbonate of soda and a squirt of washing-up liquid.
- Pour a kettle of near-boiling water over the filter until it is fully submerged. Add a splash of degreaser if the filter is very heavy.
- Leave for thirty minutes. The mesh should turn from yellow-brown to close to its original silver.
- Scrub the mesh with a soft brush in the direction of the wires, both sides.
- Rinse thoroughly under warm running water.
- Dry with an old towel and let it air-dry for another thirty minutes before refitting.
Can you put a filter in the dishwasher?
Yes for stainless-steel mesh filters — no for aluminium. Aluminium filters go grey and dull permanently in a dishwasher because the detergent oxidises the metal. If you are not sure, check the manual or take a small file to a hidden edge. Silver filings are aluminium; darker grey is steel. For dishwasher-safe stainless filters, use the intensive cycle at 65 to 70 degrees and skip the rinse aid — it can leave streaks. For aluminium, always hand-wash with the boiling-water soak.
Read also: When to replace carbon and grease filters
The carbon filter — replace, do not wash
Carbon filters sit behind the grease filter in recirculating hoods. They are usually round, dark grey and about two centimetres thick. Their job is to absorb odours by passing air through activated charcoal. Once the charcoal is saturated with grease and cooking smells, no amount of washing can restore it — it is not that the filter is dirty on the surface, the whole material is saturated. Replace carbon filters every three to six months in a busy kitchen, or every six to twelve months in a light-use one. Look up the model of your hood and buy the exact matching filter.
Signs your filter needs cleaning
Slow extraction
If steam lingers over the hob when the extractor is at full speed, the grease filter is choked.
Cooking smells lingering
That is the carbon filter, not the grease filter. Replace it.
Greasy droplets on the underside of the hood
The grease filter is saturated and grease is bypassing it.
The hood feels louder
Blocked filters force the fan to work harder.
Prevention
Run the extractor on the lowest setting whenever you cook, not just for high-heat frying. Steam and light vapour still deposit grease, and the fan working continuously at low speed builds up much less carbon than running flat-out only when the smoke alarm goes. Clean the metal filter every four to six weeks in a family kitchen, or every eight in a lighter household.
Conclusion
A clean cooker hood filter is the difference between an extractor that quietly does its job and one that just moves warm greasy air around. The boiling-water soak takes thirty minutes and works on any metal filter. Carbon filters get replaced, not washed. If yours has been ignored for a year and the whole hood is dripping, book our appliances cleaning service in London and we will strip, dip and rebuild the extractor for you.
