Run hot water in the sink. The hotter the water, the more effective it will be. If the sink has a disposal unit, turn it on. If this doesn’t clear the obstruction, try using a plunger, making sure the plug on the drain on the other side of the double bowl doesn’t pop loose. It’s good practice to apply a thick layer of petroleum jelly to the rim of the plunger before using it to ensure a tight seal, creating greater suction.
If your sink drains are chronically slow and you live in an older house, the problem may be an accumulation of sludge in the lines. No amount of plunging or chemicals will fix this. A metal snake should be used on each of the drain lines. Allow our professional plumbers to do this for you.