[beeje]

A lot of diy or half ass plumbers, install kitchen sink basket strainer incorrectly.

Most come with a black rubber washer and a cardboard ? washer.
The strainer goes in from the top with plumbers putty (or I like to use clear silicon).
From the bottom, the rubber washer goes on first, then the cardboard washer, then the nut/ring.
The cardboard washer allows the nut to spin and tighten up without grabbing the rubber washer.

A lot of installs I have seen have the rubber washer on the top side, between the strainer and sink. This raises up the strainer and does not allow all the water to drain out