There is a category of household job nobody is ever taught, and the extractor hood filter sits right at the top of it. You use the hood every day. You wipe its front when it gets splashed. And then one evening you notice that frying onions now perfume the entire flat, that the fan sounds like it is working harder, and that if you tilt your head you can see the metal mesh above the hob has gone a soft, dull, amber colour. That colour is fat. Months of it, vaporised, carried upwards, and caught exactly where it was designed to be caught.
Why it matters more than it looks
A grease filter works by forcing air through layers of fine metal mesh so that oil droplets condense and stick. When the mesh is saturated, the air cannot move through it properly, so cooking smells and steam spill back into the room instead of being pulled away. That is why kitchen cupboard doors near the hob get tacky, why the ceiling above the cooker dulls, and why fabric in an open-plan room starts to hold a faint chip-shop note. A clogged filter also makes the motor work harder and, with enough accumulated fat, sits closer to a hob flame than anyone would like.
The soak that does most of the work
Take the filter out first — most slide or click out with a small sprung catch on the underside, and you may need to support it with your other hand because they are heavier than they look. If yours has two panels, do them one at a time so you can see how they go back.
