diagram

Step-by-Step

Waste that would clog the drain is captured by the sink strainer. Its wide bowl is held snug against the sink bottom by the locknut. Putty and a rubber gasket sandwich the sink for a tight seal. The next important joint is where the strainer body meets the tailpiece. Here the seal is made watertight with a washer and a slip nut.

tailpiece

Loosen the slip nut beneath the strainer body and the slip nut above the trap bend using an adjustable wrench. Finish unscrewing it by hand, and remove the tailpiece.

locknut

Removing the locknut can be difficult, especially if it is hard to get to. Consider purchasing a spud wrench, which is specially designed to fit on locknuts. Otherwise, tap gently with a hammer and screwdriver to loosen the nut.

old putty

Use a putty knife to scrape the old putty from the drain opening. Clean the opening thoroughly with a scouring pad soaked with paint thinner. If you will be reusing the strainer, clean off the flange of the strainer as well.

reinstall

Make a rope of putty, and place it on the lip of the drain opening. Press the strainer into the opening. From under the sink, slip on the rubber gasket and the friction ring; screw on the locknut. Tighten the locknut until the strainer nests completely into the sink. Reinstall the tailpiece.