Ice blocks from vacuum bags?

Wildcat

Adventurer
i made a few polar tubes out of some pvc scrap i had in the garage. they are now in the trash because frozen gatorade bottles work better....for me.
 

yoggie

Member
I use a combination of the square water bottles and plastic 1/2 gallon milk jugs, depending on how the food fits in the cooler shape wise.

I have heard adding salt to the water before you freeze them makes the ice colder and last longer, but I am not sure if this is actually true. Anyone have any knowledge on this?
 

ITTOG

Well-known member
Adding salt lowers the freeze point of water. If you add about 20% salt it will lower the freeze point to around 0 F. Assuming you can get your freezer to 0 or lower, your ice will be colder, thus your cooler will be colder.

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ITTOG

Well-known member
Adding salt lowers the freeze point of water. If you add about 20% salt it will lower the freeze point to around 0 F. Assuming you can get your freezer to 0 or lower, your ice will be colder, thus your cooler will be colder.
Of course salty ice begins melting at lower temperature also.
That 20%, by weight or volume ?
Regardless it is still colder. It is by weight.

I found this pic online. Once you get to about 22% salt the water is saturated and adding more salt doesn't help. IMG_20181001_122201.jpeg

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john61ct

Adventurer
There is a huge amount of energy released / absorbed by the melting from solid to liquid.

If the eutectic fluid has a lower temp phase change point the cooler contents will be at that cooler temp for longer.

Glue - capped PVC "polar" tubes or other sealed containers will be more food-safe.

Can just buy eutectic solutions at different temp points.

But of course must be higher than your freezer can get down to.

12V compressor freezers use a **lot** more bank AH per 24 hours running at colder temps, like 2-4x running as a fridge.
 

yoggie

Member
ITTOG, thank you for the info on how much salt to add.

John, where does one find a eutectic solution for sale? A quick Amazon search didnt come up with anything but I suspect there is a better name to actually find it under. Also, I dont care for the shape of the polar tubes. It seems there is a lot of wasted space around them. Perfect idea would be a sealed set of bricks that are shaped (or closely shaped) to the bottom of the cooler. Granted, the simple freezer packs and gel packs could fit that bill without having to build something. And at like $2-3 each, they are not exactly expensive. Granted, you cannot thaw them and have drinking water, but same goes for a salt solution as well.
 

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