Why is store brought ice clear but when you make it at home it goes cloudy?


Title says it all really, the store brought ice is always very different. Why is this?

Edit: I know I’m a moron, bought*

In: Chemistry

They use a different process to make ice more efficient and quickly. Instead of putting the water into a freezer and cooling it with air they spray/pour water directly on the coils of the freezer. This makes it form in a bunch of thin and quickly formed layers, instead of as one thick chunk which is frozen slowly over dozens of minutes.

When ice is formed in a big chunk it freezes from the outside in. So a layer on the outside forms, and then the inside of it is stopped from expanding and can’t push itself out, which makes a bunch of stress lines/fractures throughout the cube. This is also why ice cubes from your freezer will ‘pop’ or sometimes explode when it’s melting in your glass.

None of this happens when the ice is formed in layers from one direction because the water has room to expand.

Water has air dissolved in it. If you freeze it in your freezer, the outside freezes first, trapping the air in the middle. When the last of the water in the middle freezes the dissolved air is forced out, leaving a cloud of tiny bubbles in the ice.

The factory ice is frozen from the bottom up. There’s always a layer of liquid water at the top as the ice block grows from below, so no air is trapped inside.

Ice cubes all start as “clear” as they freeze (assuming clear water ofc), but they get cloudy due to the internal stress since ice cubes freeze from outside to inside. You can even see this yourself if you look at half-finished ice-cubes, as the ice is still (mostly) clear.

Industrial / professional ice cubes are made differently, for example by taking the ice out before it is entirely frozen:


It’s because tap water has other impurities in it that get frozen along with the H2O. In industrial ice making they agitate the water to release any trapped air so as it freezes all the impurities rise to the top where they can be easily removed.


Everyone is also forgetting directional freezing. When you freeze ice cubes they are small enough that you freeze the entire thing rather rapidly and since water freezes outside in if you freeze from all sides equally it traps impurities. If you insulate 3 sides and have a bigger container than just your normal ice tray you can slowly freeze from the top down. This let’s the impurities stay in the water as the top layer becomes clear ice.

My dad actually fixes these machines and we share an office. Our ice machines at home /ice trays at home just drops water into a small ice tray and freezes it. A lot of air gets trapped and that’s the white you see.

The very expensive clear ice machines have water constantly running over a very cold plate, and the cold plate freezes the ‘bottom most’ water until everything is frozen. The method of ‘running’ also ensures that air doesn’t get trapped and turn the ice white. These industrial Machines are incredibly expensive, though.

I’ve been down the rabbit hole on my quest for perfectly clear cubes, like you get at super swanky cocktail bars. I have answers now.

Boiling your water doesn’t do squat. Not sure what everyone is going on about. It’s about air and other impurities. Water has tiny bubbles. If you trap air in the middle of the cube, by freezing the cube from all direction, it will be cloudy.

Also, water expands when frozen, which causes stress as it pushes against the walls of the tray, which causes fracturing. To get clear ice, you have mimic how water freezes in a lake, which is how we used to harvest ice before electric freezers were invented. In a lake the water freezes in one direction, starting as a thin layer on top and expanding downward. As it does this it forces air and other impurities down. Because lake ice doesn’t reach the bottom of the lake, there’s always water below it, where the impurities can go.

You can do this at home by freezing water in a cooler without a lid. The ice will form top down. Pull it out before it freezes completely to the bottom.


* Youtube tutorial on using the insulated cooler method: https://www.youtube.com/watch?v=bUHcCHbgX_o
* Or if you have more money than time: https://www.truecubes.com/store/true-cubes-tray

If you want clear cubes use directional freezing. This forces the impurities to the bottom. You don’t need to boil water or use distilled water. Just a insulated cup/cooler and mold.


my dad makes really clear ice balls at home by putting a circular mold filled with water in a thermos, also filled with water, in the freezer

I’m a little retarded so I thought this said why is store bought ice cream clear and I spent probably 2 minutes trying to decipher what the fuck this meant, and who’s ice cream was clear

Engineer of very high end appliances here (has a Z in the name). Our executive team wanted clear ice badly because the customers thought that it was contaminants etc in the ice making it cloudy. When I asked my coworkers about this, not my project, the short answer is the cloudiness is air.

Basically when you pour water into an ice cube tray, micro-bubbles are introduced into the water. The water freezes on the outside first creating a shell not allowing the air to escape.

There are 2 methods to achieve clear ice. The first is to freeze the ice in layers, this allows any air to escape because each layer isn’t shelling in the air. The second way is to freeze the water very slowly, which usually is done with a large volume of water that takes hours to get down to temp and the air has time to escape.

The top comment mentioned freezing from the outside in, which is true, but said the cloudiness was from stress of the ice not being able to expand. Ice will expand no matter what, in fact there is no material on earth that can withstand the pressure of ice expanding. cloudiness = air, not stress.