Mathew Newton wrote in
:


Here's what I've got:

http://www.newtonnet.co.uk/permanent...esinkwaste.jpg

With the above-sink parts consisting only of a pressed plate (i.e.
there's no threaded column that protrudes through the sink hole) it's
clear that the watertight seal is actually a function of the rubber
washer *underneath* the sink. If I was going to be putting silicone/PM
anywhere that's where I'd be needing to put it but given the ridges on
the washer I don't think it'll be required.

I would probably do the thin top washer but not the compliant bottom one,
not with silicone but with one of the uber sticky sealants like Stixall,
just a smear, nothing more.

https://www.toolstation.com/stixall-...t-290ml/p77137

I would definitely do the overflow however they are very much prone to leak
and again with stixall. Best use clear or black, white can discolour.

Excess can be wiped off with a paper towel moistened with isopropyl
alcohol.