Thanks for your responses, guys.
Bernie2: Well the product I use this Dow Corning 785. Here is what the blurb says:
DOW CORNING® 785 Sanitary Silicone Sealant
APPLICATIONS:
• A one-part, silicone sealant specifically designed for the sealing of sanitary fittings, including baths, showers, sinks, urinals and ceramic tile joints. This product is mildew and fungus resistant.
Yes I do carry a few waste/basin mates and usually use these for sealing older basin wastes that have started to leak and very reliable they are, too. But I think I might be well missing an item in the kit provided – namely a chunky rubber washer. If it comes to it then a waste mate it will be.
heliotrope: Quite right, the foam gaskets do usually between the top flange and the basin but with this item there is a large ‘throat’ shaped washer that can only be fitted to the top part. Yes, I think there should be a purpose built washer to fit the groove. The diagram shows likewise but only a thin foam washer is provided.
system3: I have always found PM to be pretty mucky, claggy stuff to apply that seems to get everywhere. Maybe that is just a personal thing. Also, I have noticed a few times that PM, over time, has appeared to become brittle and ceases to be watertight. I remember hearing somewhere (ages back) that PM had been removed of “oils” it had included previously (I think, for environmental reasons). That said, I cannot seem to find any reference to this on the web. I did use some recently re what seemed to be an oversized outlet on a WC cistern in order to ‘pack out’ the larger than usual gap twixt the siphon thread. Absolutely fine for that.
vipey: I have certainly never used Boss Green for basin wastes though I know some plumbers who recommend it for compression fittings.
kay-jay: Thanks alot. Perhaps I'll give I'll give it (the PM) another bash. Cheers.
Thanks again, guys. :wink5: