StillSmart

Mash wrote:

The_blue wrote:

The only one with pure copper on the outside is the new one.. copper isn't porous, the inner core won't leak out.

I have been doing this for a while and I think I can speak with experience and certainty - if they are the newer magnetic coins (1p & 2p) they blister and then the inner will/is exposed.
I have some to hand if you need photographic evidence.

It is also worth noting that 'old fashioned' copper stills were copper for a reason and it wasn't convenience. Copper has beneficial effects on the spirit.

Try things for yourself if you like, but the recommendation for future readers of this post is copper.....or something inert such as the glass or stainless milk savers.