Ice can be as cold as you (or nature's hand) chills it.  But ice, in a cooler, at ambient temps in S. California, is going to reach 32 F after a time.  A capsule only 1" thick is not going to last a long time, regardless of starting temperature, which is why I mentioned originally that you'd want to start with a much thicker capsule.  If the capsule is frozen in a typical home refrigerator that is working well and properly adjusted, the temperature will be very close to 0 F.  As soon as it is removed from the freezer, the surface will warm to 32 F, and stay there until the whole mass is warmed to that temperature.  By that time, much of the ice will be melted, and the ice cream will be very soft.  I'd say if the original capsule is on the order of a gallon in volume, the interior should stay cold for a day or two, and give the consumer something like sloppy soft-serve ice cream, assuming it started at 0 F.  But, I'm speculating, based on experience with using gallon sized blocks of ice (in jugs for dryness sake) for cooling.  They last 3-4 days if I use 3 and have precooled food and beverage.

Dave Mc

---- Mike Miller <mwmiller@CWNET.COM> wrote: 
> Just a comment: Ice is not necessary 32 degrees F. It can be colder,
> actually much colder, much much colder. Just not hotter.
> 
> David B. can comment on this I bet.
> 
> Mike in Marin
> 
> On 3/8/10 7:53 PM, "Richard Koerner" <rjkinpb@SBCGLOBAL.NET> wrote:
> 
> > Dry ice would be too expensive; going to a nearby Ice Cream joint defeats my
> > purpose; I want to have ice cream out in the middle of nowhere!!  One tip from
> > the list was to realize that ice cream at 32 F (as in packed in ice) is not
> > the same as ice cream at 0 F (like in the refrigerator at home, which I assume
> > is something like 0 F).
> >