I understand, if you can, actual shopping wins over the virtual
variety every time.
I've had my large can of Electrosil for years - as you know, one only
needs a tiny amount to do the job (and most of it should be wiped out
of the mould before use!) I've just done a search for the product and
despite the fact that the Sunderland based company is mentioned, I
can't find anywhere which currently sells the product.Maybe that
brand's gone now.
I've checked at you-know-where (Maplin - the-shop-that-must-not-be-
named - the Voldemort of the high street) and they do have a very
similar product 'Silicone Grease with PTFE' in aerosol form - it's
reference is N71AN.
The fact that the Maplin product has fine PTFE dust in it won't do
any harm - it must be extremely finely divided in order to pass the
nozzle of the aerosol, and so won't show on the clay.
Here's the online reference - just in case....
(hope that works - if not, just do a search for the product code at
Alternatively, you could try anywhere that sells materials for
fibreglass moulding (boatbuilders, caravan refurbishers etc etc) -
they're bound to have some silicone-based releasant.
(even WD40 will work but it may shorten the life of the mould)
Hope that helps.