Installing bathroom sink drain

[tomtheelder2020]

Purchased Keeney K820-75 push button bathroom sink drain. Instruction say: 1) remove the locknut, friction washer and drain washer; 2) apply drain sealant to underside of drain flange then insert it into drain opening; 3) from underside install the drain washer, friction washer and locknut. The instruction do not mention the black washer (shown in product photo) that clearly fits between the drain flange and the sink. Questions:

1) Is sealant necessary when that washer is used? [youtube video showed generic installation without sealant]
2) If sealant is necessary or recommended, does it go above the washer, below it, or both?
3) Is there a suitable sealant other than plumbers putty?

Thanks.

 

[Snoonyb]

Either or, I used both yet prefer plumbers putty, because it doesn't deteriorate because of products used, or allowed to accumulate under.

 

[havasu]

I just installed one similar last week, which was made by Moen. The instructions said if installing on a smooth surface, such as porcelain, the instructions said no plumber's putty or sealant was necessary. Sure enough, it installed clean just using that flimsy little rubber gasket.

Obviously, your mileage may vary.