Why does my ice cream get crispy in my float? I float my ice cream with Diet Pepsi. I'm always excited for when the ice cream gets crispy. It gets crispier when I use cold soda instead of room temperature. Is my soda freezing in the ice cream?
I think I know what you mean, but is the ice cream "crispy" only on the surface? Unless your ice cream becomes crispy in its interior as well, (which I could not explain), I think it's simply as you speculate, the water in the soda is freezing into a crust of ice around the surface of the ice cream ball. This would explain why it is more noticeable when the soda is cold.