Mainly mechanical Top down you can put the the water in a small ice chest and the insulation will slow the freeze in the bulk. otherwise it freezes outside in

Mainly mechanical Top down you can put the the water in a small ice chest and the insulation will slow the freeze in the bulk. otherwise it freezes outside in That ice floats may play some role, I am not sure if for or against. I made a couple of attempts, just for fun, and found the ice chest necessary but never made a systematic study of the process.