This is as simple as it sounds.
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Kitchen sinks are notorious for clogging up. The drain develops a slimy greasy coating.
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I have used a plunger, a plunger with
hot water and
soap, and a plunger with
hot water, soap and spent
coffee grounds.
This mixture seems to work the best.
Coffee grounds are mildly abrasive, but they're not likely to stick in the trap the way that sand or something heavier might.
I boil
water and mix it with the grounds and some kitchen soap. Just
enough to fill the S trap, with a little to spare. The mixture is poured in and the plunger placed to seal off the hole completely. The plunger is moved up and down vigorously for 15 seconds or so. Done.
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I do this as a preemptive measure, from time to time.
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These simple tools are great for pulling hair from bathroom drains. See last 2 photos.
https://permies.com/t/54322/recycling-repurposing/Dale-drain-cleaning-tools-thin