Place a bucket underneath. Unscrew the curved trap beneath the sink (hand-tight nuts usually need no tools). Clean out the sludge, food particles, or tiny utensil that fell in. Reassemble tightly.
Liquid chemical drain cleaners can damage old metal pipes and are ineffective against full clogs. Also, never pour boiling water directly into a porcelain sink—run the hot tap first to avoid cracking. how to unclog double sink
After plunging, pour a kettle of boiling water directly down the drain (if you have PVC pipes, let hot tap water run first to warm them). Follow with a mixture of ½ cup baking soda and 1 cup vinegar. Let it fizz for 10 minutes, then flush with more hot water. This works best on grease or soap scum, not solid debris. Place a bucket underneath