Why does ice you buy from the store have holes in the middle? Also, why are they more clear than what a home icemaker produces?
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The hole is from the way they make it – refrigerated rods that get dipped in water, forming ice on the outside.
The ice in commercial ice makers freezes from the inside out so the dissolved oxygen is forced out as it freezes. In a standard ice tray the surface of the water freezes first and consequently traps the dissolved oxygen inside the cube, forming tiny bubbles which give the cube its opaque appearance. Domestic ice machines operate more like an ice tray than a commercial ice machine.
So it’s not that our reverse osmosis is cleaner than the city water, it’s that it fills with less bubbles than the other tap? Grrr. At least it has less dissolved gases I suppose. Sure makes for nicer looking ice.
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The answer is down to gravity.
Commercial ice machines that specifically advertise as being able to generate clear ice do so by freezing the water into ice from the top down where the water at the top begins to freeze and solidify before the water at the bottom. As the water freezes, everything in the water is forced to the bottom and this is removed. Contrary to what most people believe, trapped air in the water does not make the ice cloudy (Unless there is lots and lots of it), it’s all the bits that aren’t actually water in the water that cause this cloudiness such as minerals, chemicals, etc.
You can see this for yourself. Get a small icebox, fill it with water and put it in a larger freezer minus its lid. As the water begins to freeze, it will freeze from the top down but the water at the bottom will remain insulated and in water form for a lot longer. As a result you will get clear ice on the top and cloudy ice on the bottom if you allow it to freeze all the way through.
The reason most commercial ice has holes in it is because it is formed by slow dripping water on a metal rod that is suspended vertically and uses a cooling technique (Similar to how a can of deodorant gets really cold when you spray it) to attract water to it and begin to freeze it. This rod is vertical so the water that hasn’t frozen yet can slowly run down the frozen ice and drip away through gravity, carrying the impurities with it and thus only clear ice remaining. Then when its ready it falls or is knocked off into a collection tray, leaving a hole where the ice was clinging to the rod.
Because there needs to be room for expansion in order to allow the impurities to fall to the bottom of the freezing water, only ice of a certain larger size can be made this way, and what usually happens is the ice gets cut up into smaller chunks.
[Here’s a good tutorial on how to make clear ice that demonstrates the process.](https://www.youtube.com/watch?v=J-flw623kjM)
Water is sprayed up into metal molds that have refrigerant lines attached. As the mold cools, the water recirculates, getting colder every time until the water starts to freeze on the mold. Any particulate in the water gets pulled by gravity off of the growing ice. When the ice gets to a certain size, warm water is sprayed on top of the molds to loosen and free the ice.
Hi production manager for an ice company here. The ice in question in created by tube ice makers, we use Vogt ice machines. The way they work is this. Think of a pipe of water, you cool the outside of the pipe and to get the ice to freeze without expanding and breaking the pipe you spin the water. To do that these pipes are vertical and a cap is put in the end with holes drilled off center. The water is under pressure and is forced threw the holes causing it to spin all the way down. So inside these machines there are many hundreds of these pipes and water is pumped to the top. Once the ice is thick enough the refrigeration system is essentially reversed and the ice slides out of the tube into a cutter. Everything is stainless or bronze or food grade plastics.
[https://www.youtube.com/watch?v=RWitzPjzIAk](https://www.youtube.com/watch?v=RWitzPjzIAk) – LAZIEST way to make CLEAR ICE, nobody talks about
What store are you guys buying ice from that has holes in the middle?? Never heard of this
Also for perfectly clear ice, you need to freeze boiling water. I know that sounds like an oxymoron bit hot water is less dense, freezes faster and is more clear
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