Step 4 · Apply Plumber's Putty to New Strainer
Take a small canister of plumber's putty and warm a walnut-sized ball of it in your hands to make it more pliable. Roll the putty between your palms to form a uniform rope about 1/2-inch thick. The rope should be long enough to encircle the underside of the new strainer's flange (the top lip). Carefully press this rope of putty firmly onto the underside of the flange, ensuring it makes a complete, unbroken circle.