Only proper wine corks are good for proper mead. I mean, yeah, there is place in our life for fermented honey solution that is consumed fast, but proper mead should age like expensive wine. It's more noble than wine, after all!
Bottling mead thus is always a challenge. I've tried all kinds of methods, or course beer caps - and especially swingtops - just start leaking at best in few years. Compouns corks too, and, being low grade stuff, they are often stinky themselves. The only exception are belge bottles and fat compound corks for braggots, if corked belge way, they occasionally leak some liquid at first, but then seal themselves for good.
Even higher grade corks tend to degrade over the years. Highest grade does not degrade. I've just negotiated a sample of fancy corks from Portugal, about 1eur/cork, highest grade. They look really good and will probably work, but min order is 6000 and they have to be repackaged sterile. Good thung I have sterile line, but 6000? It's 10x more than all bottles I have now! I could place them in my webstore in small bags? Would someone be buying them?
I was looking into alternatives, but nothing so far looks promising. I'm thinking about turning other wood types on a lathe, but that will probably result in a disaster.