Science Buddies: "Ask an Expert"

I have been working on supercooling tap & salt water for my 7th grade science project. I followed the procedure's listed on Science Buddies. You mention that the temperature should reach its freezing level in about 20 minutes. It has taken me 50 - 60 minutes to lower the water to 0C. What can I do to speed up this process.
Thank you,
Mccoy_22

McCoy_22,
Thanks for your question. Welcome to science buddies. These type of experiments can be kind of tricky. Here you are trying to manipulate the heat transfer and phase change property of the water. I have two suggestions.

First: What temperature is the water at the start? You can speed up the process by starting with water that has already been cooled part of the way in a refrigerator (don't let it get too close to 0 deg C).

Second: heat transfer from the water to the ice is affected by surface area. A tall skinny glass will present more area of water to the ice vs a short fat glass which would have more area presented to the air via the mouth of the glass.

Of course, I don't know your test setup. If you could provide more info about your experiment, that would help us provide better advice.