Making ice blocks

I heard adding a percentage of rock salt to the water makes last longer. I never tried.
 
Here is some of the math: To change the temperature od water by one degree requires one Btu (British thermal unit). To change liquid water at 32°F to solid ice at 32°F requires 80 Btu. The "80" is called the heat of fusion.

To maximize the life of the ice, therefore, you want to make sure the ice is below 32° and fully on the solid side of that fusion thing.

When salt water freezes, that which becomes solid expells the salt and solidifies as pure water. You end up with freshwater ice is more and more concentrated brine. That's slush.
 
Not an additive but 1 easy trick is to refill plastic liter bottles with water and freeze them to put in coolers in lieu of block ice. They tend to last longer and can be refrozen tons of times. I,f used in a fish box, just rinse outside well afterward to prevent odors. alternately , freeze foo-foo bottled water and have a great supply if drinkable ice water as it melts.
 
quote:
Originally posted by Robyns Nest

Saltwater ice is colder than fresh water ice, thus keeps longer.

Click to expand...

???
If your freezer is at 10* and you freeze fresh water, it will eventually get to 10*; length of time depends on how big the ice blocks are. I don't see how adding salt to the water will make it get 5* or even colder. The ice, whether fresh or salt, will not get to a lower temperature than the freezer.
 
Adding salt to ice which is at 32 deg will cause the temperature to drop well below 32 deg. Obviously you have never made ice cream at home with an old fashioned maker. I may not know much about the physics or chemistry involved but I do know about ice cream. If you have made it this far in life without having had truly homemade ice cream, you have missed one of the finer points of living.
 
I think that we have some misconceptions about water, salt and ice here. Adding the salt to the water LOWERS the FREEZING POINT of that solution. That is, more BTU's have to be subtracted from the solution to make it freeze. It does not make the final solution any colder or warmer. If the freezer temperature is at 10deg. the final ice temperature will be at 10deg.

Think about why roads are salted. When the salt is sprea on the ice it causes the melting/freezing temperature to be lowered. Therefore the ice on the road will melt at a lower temperature than non-salted ice.

For the discussion at hand, think of the salt solution ice as containing (to coin a phrase) more COLD BTS's. The temperature is not any colder, it just absorbs more calories when it is melting.

G
 
I still remember :Dthe homemade ice cream that Mrs Taylor down the block made for the neighborhood kids,it was delicious. That was 65 years ago. Cant seem to remember what Ann asked me to pickup at the supermarket this AM.[:-dunce]

BTW, The ice blocks that I frose with the Tap water in the Kitty Litter buckets worked out fine.
Thanks again all.
 
quote:
Originally posted by rbmitchell

Adding salt to ice which is at 32 deg will cause the temperature to drop well below 32 deg. Obviously you have never made ice cream at home with an old fashioned maker. I may not know much about the physics or chemistry involved but I do know about ice cream. If you have made it this far in life without having had truly homemade ice cream, you have missed one of the finer points of living.

Click to expand...

I am old enough to remember the old ice cream makers. Adding salt does lower the freezing temperature but it does this by melting the ice faster which is contrary to what the OP wants to do. He wants his ice to last longer, hence not melt as faster.
The way I see it, the OP would like to add something to the water which will give the ice more BTUs for cooling or just plain increase the amount of time it takes the ice to melt. If something coul be added to the water to raise it's melting point from say 32* to perhaps 37*, the ice may last 10% longer. Anything more than that seems unrealistic. I wonder what they put in those plastic containers that you put in the freezer and then throw in the cooler.
 
"I wonder what they put in those plastic containers that you put in the freezer and then throw in the cooler." -- mandm1200

propylene glycol. "Non-toxic in the low concentration used in Blue Ice" according to the MSDS.
 
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