Sink waste drain leak

[BBT]

Hi

dyi here. I installed a new high dollar pfister faucet on a bath vanity and it was easy enough except the drain. it leaks at the washer set. things i have done to stop it.

1. reread the installation instructions and did two complete remove and installs on the drain
2. it says hand tighten and i have had to use channel locks because its a metal nut but no matter how tight or not it still leaks.
3. there is a gasket right below the top and then a fat rubber washer, a flat nylon washer and the metal nut. it says not to use anything like putty because it would degrade the material.

i have laid and watched it and tried different torques on the nut and done this for several hours over several days. its laughing at me

i wonder if the surface of the sink material at fault, it drips from the same area, sink is a cast material. should I dry the area and fill area with silicone and tighten it down and wait 24hours and check for leaks or should i try and buy a push drain that will allow putty. what would a plumber do in this situation.

thanks for any advice on steps to take,

 

[Terry]

Is the drain plastic or brass?

 

[Sponsor]

 

[BBT]

Is the drain plastic or brass?

Thanks for asking
I thought I covered every angle, lol sorry
its brass I would image with a chrome finish and has a rubber gasket under the top lid and a big slanted rubber washer with the slant pointing up and a flat nylon washer underneath on top of the metal nut.
it appears to leak at the top

there was a leak i fixed. the metal tube has about 5 threads and screws in to the top. me turning the nut would loosen it. i put one turn of fast tape on it and its solid now. but that confused me. i can see it drop from the fitting seam now above the nut

 

[Terry]

I use pipe dope on the threads where it passes through the larger rubber washer on the bottom of the lav basin. Otherwise the water can roll down the threads.
You can also push some putty in the threads in you don't have pipe dope. It's about blocking the pathway for the water.

 

[BBT]

thanks i will buy whatever i need