Before you start plunging, you must seal off air vents to ensure all force is directed at the clog: How to use a plunger correctly (and use the RIGHT plunger!)
Pumping in fast, sharp bursts is often more effective than long, slow strokes. plunger sink
The Unsung Hero of Clogged Drains: Why You Need a Plunger Sink Before you start plunging, you must seal off