does salt make water colder

[morrillt]

Ok so I am trying to get my beer as cold as possible for bottling.

I have googled this immensely.

I understand that salt lowers the boiling point of water.....

But if I just add salt water to my ice bath around my keg will the ambient water get below 0?

I broke my thermometer that goes below 0, or else I would just do this myself

 

[Hobanon]

Not sure about 0, but it will definitely get the water colder than freezing. Mythbusters did this and I think it chilled a sixer in like 30 mins?

Edit: why do you need it cold to bottle? Are you trying to cold crash for clarity?

 

[imasickboy]

Yes.

 

[ZebulonBrewer]

It does, but not by a lot. If I remember my chemistry it takes a fairly high concentration to get the freezing point to drop more than a couple degrees. If you really want to keep a fermenter cool you're better off utilizing evaporative cooling over a lower water bath temp. (source, several masters thermo-fluid courses)

 

[ChelisHubby]

salt will lower the temp a couple of degrees of when the water freezes. if the ice bath has no water you might get a small benefit, as the ice melts it should be a little colder than 32.

 

[morrillt]

I found the thermometer. I was able to drop it 5 degrees celsius by adding salt, thats like 10f.... fyi. I have a foaming issue when i bottle at serving temps (38f)

 

[CA_Mouse]

I found the thermometer. I was able to drop it 5 degrees celsius by adding salt, thats like 10f.... fyi. I have a foaming issue when i bottle at serving temps (38f)

Lower the pressure on your keg to 2 psi and chill your bottles for an hour in the same fridge as the keg.

 

[Spartan1979]

Salt doesn't lower the temperature of water, it just lowers the freezing point.

 

[JKoravos]

I found the thermometer. I was able to drop it 5 degrees celsius by adding salt, thats like 10f.... fyi. I have a foaming issue when i bottle at serving temps (38f)

I think you're attacking this the wrong way. Wasting a bunch of salt and making it more complicated. If you have foaming you are likely just pushing it too fast (unless we're talking belgian carbonation levels). If you can serve at 38F without major foaming, bottling shouldn't be an issue.

Do as CA_mouse said above. Gently purge the gas in the headspace of the keg until you get down to 2-3 psi. If you purge slowly you shouldn't have any issues with foaming in the keg. Adjust your regulator to keep 2psi in the headspace. The idea is to keep some backpressure to allow you to maintain a low flow rate when bottling. This should eliminate foaming as long as your CO2 volumes are under about 2.6-2.8.

I carbonate my beers with 11 psi at ~37F and I can easily bottle right off of a picnic tap without foam if I purge the headspace and dial the regulator back to 5psi.

Maybe tell us more about your bottling process. There could be other things causing the foaming.

 

[DeeEnvy]

I understand that salt lowers the boiling point of water.....

Sorry but that statement is incorrect. Salt increases the boiling point of water.
Just had to clarify.

 

[JKoravos]

Correct, elevates boiling point, reduces melting point.

 

[PlexVector]

Just like in making home made ice cream in a churn. The salt melts the ice to create more contact area with the sides of the container and still be below freezing. I haven't done this in a long time, but ice cream salt used to be cheaper than using table salt--maybe is still.