On 25/10/2020 11:36, Mathew Newton wrote:
I've got a new stainless steel Franke sink and waste, which came supplied with sealing washers top and bottom. The instructions make no mention of using any silicone in addition to the washers but should I for belt and braces?

I'd expect Franke to have well finished parts and good quality seals and
screwing bits, in which case you should not need silicone.