Crisco in Freezing Water?

Most recent answer: 10/22/2007

Q:
How does the amount of crisco in water affect how water freezes?
- jeff
A:
Crisco, and other shortening products, are made of oils and other fatty molecules called lipids. These substances do not dissolve in water and do not change the water’s properties. Crisco is lighter than water and will float on top of it. Crisco is also a lousy thermal conductor, and a layer of it on top of your water not only will prevent thermal conduction, but also reduce the evaporation rate. If the top of your water tray is entirely covered in crisco, there will be no evaporation.

Evaporation helps to cool water down quickly (but you lose some water in the process). Your ice should be the same whether or not it has crisco on top of it, but you may have ever so slightly more of it and taken longer to make it if there is a layer of vegetable shortening on top.

Tom

(published on 10/22/2007)