I have a confession...

A friend and I took our icecream makers and mix and ice and salt to an
outdoor party, and set it up so we would all have an after dinner treat.
Well over an hour later (it might have even been two) we barely had a light
slurry, despite using plenty of ice and salt. The only thing I can think of
is that I used mostly heavy cream, and some half-and-half- I didn't use
much regular milk in the mix. I know it doesn't freeze hard- we used to
make icecream when I was a kid- but this wasn't freezing at all, not even a
light milkshake consistency.

Is there some level of fat content at which an icecream maker simply can't
make the icecream?

Thanks,
Keith