Adding salt to water and ice to cool down wort?

I was watching Mythbusters tonight, and they ran an experiment to test the best way to cool down a six pack of beer. They timed how long it took to take a six-pack from 62.9 degrees (ambient temperature) to the ideal drinking temperature of 38-40 degrees.
They put a six pack in a cooler full of ice,
They put a six pack in a cooler full of ice+water,
They put a six pack in a cooler full of ice+water+salt,
and they put a six pack in the freezer.

It took only 5 minutes to get the six pack to 35 degrees using the ice+water+salt method. It took much longer for the other methods. The salt somehow speeds up the cool down process (I missed the science'y explanation they gave). This got me thinking, should I do this the next time I brew? Right after the hour long boil, when I have my brew pot in the sink, would the increased speed of cool down be beneficial?
Has anyone ever done this?

As I recall, salt lowers the freezing temp of water allowing it to get colder without freezing.

Bruscar said:

As I recall, salt lowers the freezing temp of water allowing it to get colder without freezing.

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Bingo!

Saltwater has a freezing/melting temp of 29 degrees F. something like that. Thats why adding rock salt to the ice in a hand crank ice cream maker freezes the milk mixture.

A box of rocksalt at Wal Mart cost a buck or something. try it, its cheap

oh, SO CLOSE. English is not the most specific language... not that I know another...

The scientificy explanation probably went something like this:

(A) Salt will lower the temperature at which water will freeze...
so you can keep water as a liquid at temperatures lower than pure water by adding (a) salt.


This has many advantages. For one, you increase the surface area of material contacting the bottles that is lower than 32F by a lot.

I like that. Nice post, may try this next brew.

I use a pre-chiller (my old 25 ft wort chiller) in a pot with ice and salt. Seems to work decently well.

Buford said:

I use a pre-chiller (my old 25 ft wort chiller) in a pot with ice and salt. Seems to work decently well.

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Might give this a shot with my prechiller.

Is the copper ok in salt water?

What ratio of salt to water? Do I just get ice, throw some water in, and dump a whole lot of salt in?

Typical salt:water ratios are 1:5 to 1:10. 1:5 will give you about 10F.

Historical note: 0F is the lowest temperature that you can achieve with water, ice & salt. It was picked because is was easy to duplicate. At the other end, 96F was supposed to be blood heat. Oops.

Brew Dude said:

...the ideal drinking temperature of 38-40 degrees...

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Says who?

homebrewer_99 said:

Says who?

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It was BMC.

Yeah, that should work great. It's called boiling point elevation/freezing point depression. Cheers!

Cool, seems like I'm not the only person who didn't know about this.

One question, would saltwater be corrosive to stainless steel? My father in law seems to think so since he lost a ton of stainless steel parts on his boat to saltwater.

denimglen said:

Might give this a shot with my prechiller.

Is the copper ok in salt water?

What ratio of salt to water? Do I just get ice, throw some water in, and dump a whole lot of salt in?

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It'll probably corrode the copper over time, but I don't know. I rinse the chiller off immediately afterwards to get the salt off, though.

I just dump some table salt in on top of the ice, I don't measure it.

Buford said:

I use a pre-chiller (my old 25 ft wort chiller) in a pot with ice and salt. Seems to work decently well.

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Same here.

4 inches of ice. Some rock salt...4 more inches of ice..some more rock salt....you get the idea.

Think of the homemade ice cream makers. Salt is essential to creat a sub-freezing temperature to freeze the cream mixture.

BierMuncher said:

Think of the homemade ice cream makers. Salt is essential to creat a sub-freezing temperature to freeze the cream mixture.

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Never even seen one of these things haha.

Thanks Buford and David_42, boiling wort at the moment so will be testing it out in a minute. Cheers.