When I was working on an ice climbing robot we spent a lot of effort trying to get large blocks of clear ice to test on. The thought was that we wanted repeatable experiments. But then we realized that perfectly dense water ice is so hard and tough that our robot would not be able to get an ice screw into it. So we ended up trying to make something more similar to glacial ice. To do that we bought a nugget ice machine, filled large aluminum bins of that, and then backfilled with water, and had the robot climb on those in a walk-in freezer.
Former bartender here. Having nice cocktail ice chunks at home isn't as complex as this might make it seem. No need for a clunky box in your freezer or costly gizmos.
I keep a travel-sized coffee thermos in my freezer with about 2-3 inches of water at the bottom. Takes 18-24 hours to create one chunk. If you time it right, 90% of the water freezes, and the water impurities pool at the bottom – pop out the frozen chunk and the result is clear ice. I store 4-5 of these in a zip-top bag until I have friends over and serve drinks.
Best to use a thermos with a slight conical interior so it's easy to pop out the ice. Makes a nice plug-shaped, clear ice chunk. Then refill and restart the process.
In the lab one of the cool things is to take a 100 mL pyrex tall-form (Berzelius) beaker about half full of DI water and set it on top of a little slab of dry ice which is at the bottom of a small bowl.
Then pack some crushed dry ice around the beaker and the water starts to freeze quite quickly from the outside in.
When the frozen water is about 5mm thick, remove the beaker, pour out the liquid water and return the beaker to the dry ice nest until it's quite a bit colder.
The ice in the beaker continues to shrink and can then be removed from the beaker "mold" as a shot glass made of ice.
Caution: do not handle it with bare hands, nor consume any contents at this point until it is no longer very far below 0.
Best to allow these ice glasses to "warm up" to a comfortable temperature in an ordinary freezer before use.
It will then withstand pre-chilled liquor for a number of minutes after serving.
An even lower equipment option I've had some success with:
Just use any food container, such as an ice-cream box or tupperware. Part fill it and put in the freezer with no lid. It will start freezing from the outside in. When it is partly frozen but before it goes cloudy, break a hole in the top of the ice to allow the trapped liquid inside to escape, and put it back in for a few more hours until it is nearly all frozen. This way you can get a big mostly clear block with a cloudy bit in the middle (you can repeat the break and freeze to get it even smaller), which you can cut up and melt off any cloudy bits with warm water.
But also as the ice freezes I believe it becomes more buoyant and that rigidity causes the ice to be lifted up when it exerts force on the thermos interior.
Not an issue. It's only partially filled, less than half-way. As it forms, the ice floats and glides up the sides until it's like, 1mm higher than where it started.
I’ve purchased this one[1] and it makes almost perfect cubes of ice that are very clear and melt evenly and slowly. In my cocktail glass it is so flat that the whiskey does not permeate the bottom. The result is a beautifully clear square in the center of my glass when looking at it from above.
Trick is to let the ice temper for a few minutes to acclimate to the room temperature before pouring your drink over it. Otherwise it will crack. Also good to spin it a few times in your glass to melt it a bit to get it perfectly flat.
[1] ClearlyFrozen High Capacity (10 x 2 Inch) Home Clear Ice Cube Tray/Ice Cube Maker https://a.co/d/2E7YcmC
The margins on that must be incredible. An ice cube tray plus some foam packing material, for $40. Didn't even bother to encase the foam in a blow-molded shell like a cooler.
They have created a few "innovative" products, such as larger "clearer" ice cubes for cocktails - related to TFA - by spraying water into super cooled upside-down moulds.
Sounds like similar tech to the Kold-Draft machines in the US market.[1] During the height of the pandemic one of my neighborhood bars was selling bags of their cubes to stay afloat. Only good thing to come out of covid.
In case anyone wants an easy way to make nice, clear ice fairly easy in a home setting.
https://www.wintersmiths.com/ - These guys make gadgets that you can put in your freezer and get very clear ice. Melt very well/evenly.
You can also find details of their latest machine on kickstarter, which is a work in progress.
edit: I have bought most of their products over the years, starting with their first ice-baller. And supported the phantom kickstarter, and their latest one.
I've gotten excellent results using an aquarium pump in a cooler. Essentially making a tiny Clinebell ice maker in your freezer. If you position it right and use the right amount of power, you get zero cloudiness at any point in the block. Best sample I was able to make (the second slide is more impressive, not sure why I didn't post that first): https://www.instagram.com/p/BfRgI71B1h7/?hl=en
Major hassle though. And is the aquarium pump food safe? Probably better to go with the directional freezing method.
Regardless, I'm pretty sure Camper English mentions this somewhere in his archives - he's tried every single method as far as I can tell. He is the godfather of clear ice.
I also recommend storing your specialty ice in a brown paper bag. It'll keep for a surprisingly long while without sticking to each other!
I have a premade directional ice kit and make 10 ice cubes per night and then throw them into the paper bags. We never run out of ice for weekend gatherings with this trick.
You might mean air, not oxygen. Air is mostly nitrogen. Water ice is 1/3rd oxygen atoms (or about 8/9ths by mass).
Thinking more, molecular oxygen, O2, dissolved in water is a thing and it does have better solubility than nitrogen so maybe you did mean molecular oxygen.
And yeah, we tried that, putting water in a vacuum chamber and pumping out the dissolved air. It didn't seem to make much difference.
Doesn't really work – the real trick is to make sure your ice is crystallizing directionally. The impurities are the last to crystallize, so this pushes them out.
Then you take your ice out of the container when it's 90% done, and your ice chunk is clear.
That isn’t the issue. The problem is an ice shell initially forms, then the water inside the shell needs to expand as it freezes but it has no where to expand. This creates internal stress and micro fractures and the resulting ice crackles due to internal stress. Clear ice requires a directional freeze.
Hm. This internal stress issue you describe might be a thing, but I'm pretty sure bubbles exsolving during freezing is also a thing. Most of the times I tried and failed to make clear ice there were obvious bubble exsolution trails.
Faster freezing is bad when you're trying to make clear ice. It's also bad to put hot water in your freezer - you're bringing the temperature of everything else up and then it has to refreeze. That'll damage the quality of whatever food is in the freezer.
Readit News
https://eos.org/articles/meet-iceworm-nasas-new-ice-climbing...
I keep a travel-sized coffee thermos in my freezer with about 2-3 inches of water at the bottom. Takes 18-24 hours to create one chunk. If you time it right, 90% of the water freezes, and the water impurities pool at the bottom – pop out the frozen chunk and the result is clear ice. I store 4-5 of these in a zip-top bag until I have friends over and serve drinks.
Best to use a thermos with a slight conical interior so it's easy to pop out the ice. Makes a nice plug-shaped, clear ice chunk. Then refill and restart the process.
Then pack some crushed dry ice around the beaker and the water starts to freeze quite quickly from the outside in.
When the frozen water is about 5mm thick, remove the beaker, pour out the liquid water and return the beaker to the dry ice nest until it's quite a bit colder.
The ice in the beaker continues to shrink and can then be removed from the beaker "mold" as a shot glass made of ice.
Caution: do not handle it with bare hands, nor consume any contents at this point until it is no longer very far below 0.
Best to allow these ice glasses to "warm up" to a comfortable temperature in an ordinary freezer before use.
It will then withstand pre-chilled liquor for a number of minutes after serving.
And even if you don't, worst case you end up with a cloudy end on your clear ice that can be easily removed by rubbing it on an aluminum sheet pan
But also as the ice freezes I believe it becomes more buoyant and that rigidity causes the ice to be lifted up when it exerts force on the thermos interior.
I've seen some other ideas like freezing water in a camping cooler with its top open.
From the post you’re replying to: 2 to 3 inches of water at the bottom … expands to fill the thermos
Air compresses. A lot.
From 10 seconds of Googling, something like this: https://browzefactory.com/products/tumbler-stainless-steel-2...
Trick is to let the ice temper for a few minutes to acclimate to the room temperature before pouring your drink over it. Otherwise it will crack. Also good to spin it a few times in your glass to melt it a bit to get it perfectly flat.
[1] ClearlyFrozen High Capacity (10 x 2 Inch) Home Clear Ice Cube Tray/Ice Cube Maker https://a.co/d/2E7YcmC
This is a good article from a couple of years ago about them: https://www.theguardian.com/news/2020/dec/10/super-cubes-ins...
They have created a few "innovative" products, such as larger "clearer" ice cubes for cocktails - related to TFA - by spraying water into super cooled upside-down moulds.
1: https://kold-draft.com/pages/why-kold-draft#technology
https://www.wintersmiths.com/ - These guys make gadgets that you can put in your freezer and get very clear ice. Melt very well/evenly.
You can also find details of their latest machine on kickstarter, which is a work in progress.
edit: I have bought most of their products over the years, starting with their first ice-baller. And supported the phantom kickstarter, and their latest one.
Major hassle though. And is the aquarium pump food safe? Probably better to go with the directional freezing method.
Regardless, I'm pretty sure Camper English mentions this somewhere in his archives - he's tried every single method as far as I can tell. He is the godfather of clear ice.
I have a premade directional ice kit and make 10 ice cubes per night and then throw them into the paper bags. We never run out of ice for weekend gatherings with this trick.
https://www.alcademics.com/2017/10/boiled-versus-rested-wate...
(Works somewhat, but not well enough)
Thinking more, molecular oxygen, O2, dissolved in water is a thing and it does have better solubility than nitrogen so maybe you did mean molecular oxygen.
And yeah, we tried that, putting water in a vacuum chamber and pumping out the dissolved air. It didn't seem to make much difference.
Then you take your ice out of the container when it's 90% done, and your ice chunk is clear.
https://en.wikipedia.org/wiki/Mpemba_effect
Deleted Comment