saltwater block ice

[spapstick]

does anyone make their own salt water ice? if so what mix do you use. i mixed up a heap in plastic bottles using around 3/4 salt and rest water and the salt froze but the water didn't. it was in the freezer for 2 days and has me stumped why the water didn't freeze.

[A_DIFF_PERSPECTIVE]

Salt water has a lower freezing point than fresh water, hence the reason why salt water ice is colder than freshwater ice. Fresh water freezes at
0 deg C, while salt water freezes at approx -4deg C( i think, or somewhere close to that mark.) if you add a bag of party ice to a bucket of sea water, then add some beers, you will freeze your beer as beer freezes at about 0 deg C and the sea/salt water slurry you made with the ice and sea water will get down to say roughly -3 deg C because of the salt content! When fishing, the coldest possible 'slurry'(ice and water mix) is sea water and ice, not fresh water and ice. If you are packing food for travelling, sprinkle a tiny amount of salt on your ice, this lowers the temp of your freshwater ice and prolongs the shelf life of your product.
I don't think a standard household freezer would freeze your salty water properly. Ice needs to be frozen, and then let sit to 'cure' for about a week to be of any real use for prolonged trips. Frozen blocks of ice, salt or fresh, that sound like broken glass when being handled are well cured. Ice goes opaque when it is cured. Transparent blocks are usually those types of ice that haven't had time to cure, and often melt when you are looking at them, just like servo party ice! Ice that sticks to your feet and fingers is real ice.
any more info on this topic is appreciated,
Johnny M

[Camo]

If I can remember my high school science correctly, pure water freezes at 0C, water that has salt dissolved in it has to be colder than that before it will freeze. If the water has as much salt dissolved in it as it can hold (called a saturated solution of salt), so that any further salt put into it would just come out as crystals, the freezing temperature should be around -21 C. If your freezer temperature isn't between 0C and -21C depending on the amourt of salt in the water, then it won't freeze. My suggestion would be to turn the temperature of the freezer down as low as it will go and see if it freezes. If it dosn't dilute the salt water with fresh water until it freezes. At some point it's freezing temperature will be the same as the freezer temperature and you'll have some ice.

cheers,

camo

[A_DIFF_PERSPECTIVE]

i forgot to add, -40 degrees celcius is a great temp from a freezer for making and curing ice, but unfortunately i don't have one at home!

[hoga]

i put sea water in 5 liter plastic bottles it takes about 3 to 4 days to freeze put them in uder floor fish box with a bit of sea water the fish are almost fozen by the end of the day ust refreeze for next trip hoga

[Cheech]

What is the salt content of sea water? I use 2 litre juice bottles. Works great and can leave them in the esky for 24 hours without them fully melting. I have a fish freezer so have them permanantly frozen, which by the sound of it is assisting in making them last longer. But if adding a bit of salt is more efficient then why not. But how much to add per litre? Are we talking a teaspoon or half a cup per litre? has anyone experimented and know for a standard freezer temp. Save me having to trial and error.

Cheech

[spapstick]

cheers lads i reckon i will fill my bottles with sea water and see how i go. don't think my standard freezer will get down to -20. just gotta love a cold slurry to put any fish you will fillet and skin in but watch the frozen beers. have a good one

[PinHead]

i forgot to add, -40 degrees celcius is a great temp from a freezer for making and curing ice, but unfortunately i don't have one at home!

I could make you one..for a price..LOL

[PinHead]

The freezing point of your salt water solution will be dependent on the freezing point depression of your solution...do a google search and it will tell you all about it...too much to type on here regarding this.

[FNQCairns]

I have a bad habit of checking the temperature of stuff ::) on occasion. Most freezers will happily get down to -19 if left alone.
Seawater is variable but around 30g salt per litre. I double this and can get salt water to freeze, #it also dissolves OK after a few shakes.
Dont forget that frozen saltwater cannot be consumed if needed like freshwater if the need ever arises :o.

cheers fnq

[FNQCairns]

Snapstick you over-saturated the entire mix, the water became a salt saturated brine (liquid) so needs a very low freezing point but the undissolved salt stayed in a more or less solid state being moist.

This solid accepts cold easier than the brine liquid so it was able to freeze and probably pulled a lot of cold from the brine in the process. The solid would also reach room temp faster than the brine so would probably be no better than just frosen freshwater in the esky.

It takes a lot of energy to raise or lower a L (1kg) of water 1 deg more so than any naturally occuring and common solid if my memory serves me.

cheers fnq

[maxis]

I prefer to stick with the fresh water ice in bottles just in case ya have to drink it for a few days. but hey thats me just saftey concoius or watever.

[spapstick]

cheers fnq that explains it the old chesty has no hope then! gonna go and take em out and give the old girl a rest. might go for the 60 gram a litre method cheers mate

[Heath]

We use ice from saltwater in summer. Lasts longer for them summer mackerel sessions. Use freshwater in winter.

[Daintreeboy]

Sea water is 35 parts per thousand which is 35 grams per litre. Freezing salt water is brilliant for extending your ice on long trips but a waste of time on anything less than two days. You should just have enough for the trip with normal ice. Be careful if you are using it for camping as leakage could rust your car out!
If you have a layer of salt ice on the bottom and put fresh water ice on top, the fresh ice will melt and freeze when it hits the salt ice, hence the improvement on extended stays somewhere.
Cheers, Mark.