Step #4: Apply Plumber’s Putty to Sink
After the sink and strainer are clean and dry, scoop out a golf ball sized glob of plumber’s putty, and knead it with your hands for several minutes to warm and soften it.
Once the putty is soft, use a back and forth motion with you hands to roll it into a rope of putty half an inch in diameter that’s long enough to go around the strainer opening in the sink.
Apply the putty around the sink opening, pressing it down in place. Insert the strainer in the sink opening, and press it firmly down so that putty oozes out all around it.