In article ,
clifto wrote:

Mark wrote:
Then the answer is not so obvious...

Ice/water at 32 or ice at -20?

Depends. How many square inches of contact surface? I bet 100 square inches
of 32F water will cool to 35F faster than 3 square inches of -20F ice.
Especially so if the ice forms a skin of water between ice and beer can,
limiting the interface temperature to 32F.

The total contact area of the ice has not been brought up before, IIRC,
and it's certainly relevant. As far as a "skin" of water forming, ice
skaters, so I've been told, actually skate on a very thin layer of
water.