on silicone rubber yes, on natural rubber (not much stuff is natural rubber nowadays) then Candle wax rubbed in according to my late ex step father in law who owned a rubber factoring business.Ah…..so I'm not alone @Loz.....do you have a particular favourite that you'd recommend? I did wonder if it was a pointless exercise? Am I right in saying only silicone sprays are safe on rubber components?