Step 2 · Install the New Drain Flange
Take a golf-ball sized amount of plumber's putty and knead it until soft. Roll it between your palms to form a uniform rope about 1/4-inch in diameter. Drape this putty rope around the underside of the new drain flange, pressing it on gently. Insert the flanged end of the drain into the sink's drain opening from above. Press down firmly and evenly to create a preliminary seal, causing some putty to squeeze out around the flange. From underneath the sink, slide the large rubber gasket up over the threads of the drain body until it sits flush against the bottom of the sink. Follow this with the friction washer (if provided) and then thread on the large locknut. Hand-tighten the locknut as much as you can. To complete the seal, use channel-lock pliers to tighten the locknut an additional one-half to three-quarters of a turn. This will compress the rubber gasket. Go back to the sink basin and use a rag or your finger to wipe away the excess plumber's putty that squeezed out.