Experiments in Making Cocktail Ice | Hacker News Reader

Experiments in Making Cocktail Ice

alcademics.com

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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.

https://eos.org/articles/meet-iceworm-nasas-new-ice-climbing...

That’s incredibly cool, thanks for sharing it!

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.

>If you time it right, 90% of the water freezes, and the water impurities pool at the bottom

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

I'm not sure it will be so easy to get the ice out if you let it freeze solid.

Well luckily there’s an easy solution for that as well: letting it sit for awhile.

Aluminum is a fantastic heat conductor. You can slice ice using a non-sharpened aluminum flat, easily.

Or just passing the cloudy bit under hot water. Melts like a charm.

Have a particular one to recommend?

Whatever's cheap and slightly conical – most will do. Worst case you let it sit for ~1h so it melts a little.

From 10 seconds of Googling, something like this: https://browzefactory.com/products/tumbler-stainless-steel-2...

Water expands when it freezes, in my head thermos is an extremely rigid structure, how do you stop it from rapturing?

Simply don't fill it to the brim, allowing room for expansion.

The thermos is mostly full of compressible air

I think the idea is leaving it open so it freezes from the top down. From what I've read there, the trick of clear ice is directional freezing.

I've seen some other ideas like freezing water in a camping cooler with its top open.

That's what I thought the idea was, too.

But then, why aren't my ice-cubes made in the regular fridge tray clear? The same principle should apply: they should be clear at the top, where the tray is open.

The thermos wall is an insulator, unlike the tray.

Ice in a tray freezes from all sides since it's not insulated. And indeed, the ice from your tray is crystal clear on the sides, with the cloudy ice at the center of the cube.

In an insulated vessel, the sides and bottom remain liquid until the frozen portion grows down from the top, pushing the cloudy bit to the bottom, which you can then just lop off.

I'm not sure if your end of the world planning needs to include your thermos.

Only if its completely full. A travel thermos is ~6 inches deep and OP said to fill it to 2-3 inches.

> how do you stop it from rapturing?

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.

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.

Well you make sure it isnt baptized.

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.

Pun of the year.

Will be trying this. Thanks for the tip!

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.

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.

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

I use this product too, love it!

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.

I would have thought so, and that still could be true, but the knock off brands are nipping at the heels on price. Curious.

Unshortened link: https://www.amazon.com/dp/B078ZM3F8G

Somewhat related interesting fact, the UK ice market is dominated by one player who has brought out almost all other manufacturers, The Ice Co.

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.

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.

1: https://kold-draft.com/pages/why-kold-draft#technology

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.

I always thought the key to getting clear ice was to boil the water first so the oxygen goes out of solution.

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.

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.

Interestingly freezing hot or boiled water can be quicker due to the Mpemba effect.

https://en.wikipedia.org/wiki/Mpemba_effect

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.

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.

I’ve been making clear ice for a decade. Even gone as far as an aquarium bubbler and nichrome wire setups. What you think are obvious bubbles are not actually bubbles.

Just put a double walled insulated cup in the freezer. The internal stress explanation accounts for 98% of the result when you think through how the crystal growth happened.

Sounds like we need an experiment. The best one I can think of is to freeze ice in presence of a tracer gas and then check if that gas is released upon melting. I'm not sure I could pull that off. Got any better ideas?

Just compare frozen boiled water and aerated tap water. Both will be cloudy when made in a tray and both will be clear when made in an insulated cup. It does make a minor difference, but it is unimportant.

Also notice the radial pattern that the internal fractures take. This is inconsistent with bubbles and perfectly consistent with internal stress due to expansion pressure.

I think the effect of boiling is negligible because air dissolves back into the water as the water cools. I don't understand your radial pattern argument. When I look closely at the lineations in the ice I see that the streaks are composed of individual spheroid voids. Not sure how fracture could do that.

You can pour water straight from the kettle into the trays and cover it.

https://www.dreamstime.com/stock-photo-ice-cubes-image179488...

In that photo I see a few gas bubbles, but it is dominated by radial expansion fractures and cloudy high pressure ice in the center. That ice will crack when put in water. Clear ice does not crack.

This site has whole sections on "things that don't work" and "things that work, but not that well" based on experiments. Here's boiling water first:

https://www.alcademics.com/2017/10/boiled-versus-rested-wate...

(Works somewhat, but not well enough)

Someone gonna come up with Czochralski process for monocrystalline ice :)

Excellent work! I think it was this person that launched my own home ice making journey.

My process is simple and involves freezing in quart containers and then carving with a steak knife and rubber mallet. Watching the freezing process has been neat, at one point I get a shell that could be used as a glass by itself.

This might be covered by the literature but my observation is that the ice becomes cloudy late in the freezing process which makes me suspect the issue is small fractures or imperfections in the crystal as a consequence of mechanical forces - the ice tried to occupy an area that is just a touch too small. This doesn't gel with other folks observations however who see cloudyness before the ice fully finishes freezing.

is it me or pretty much all of those icecubes are infested with air bubbles?

i'd think the "cocktail ice" criteria would be to be 100% clear. I make my own ice, usually in the winter, because it's fun when it's -20 outside and i stock pile it in a deep freezer for the remainder of the year.

process: + fill a small cooler almost to the top with water + leave the lid open and leave the cooler outside over night, or 2 nights, depends on the size + *key*: you want to remove the ice from the cooler before it freezes all the way through, ideally you want ~2 inches of water left on the bottom unfrozen. ice freezes from top to bottom, so all the air and impurities keep getting pushed down. this top layer will pretty much be perfect, you may have to wash off the top layer due to frost/snow that have accumulated over night. +. take your new slap of ice and score it with a bread cutting serrated knife, tap the knife with a wooden spoon and you'll have a perfect cut of a of a huge chuck of ice. keep serrating/hitting into smaller chunks.

Boiling water before freezing is another way of removing dissolved gases.

Tested on this very website!

https://www.alcademics.com/2017/10/boiled-versus-rested-wate...

Conclusion they came to (your opinion may vary) is that it's not worth the time and energy to get e.g. 1/2" more clear ice.

The author of the website not only describes this exact method but he also invented the method.

If you scroll to the bottom of this page you can see an example of perfect clear, if not smoothed, ice:

https://www.alcademics.com/2017/05/how-to-monogram-your-ice-...

I've been making clear ice at home for a while--it's a great party trick and much easier to do than it seems.

The best part is chiseling ice cubes from a large clear block of ice: use a serrated knife and a hammer and you will end up with perfectly square blocks of ice.

Interesting trick!

In one method he uses a silicone mold to make a clear ice ball. Note that these molds are also available for making four, six and 25 ice balls, so this may be a more efficient method than it looks, and no wire should be required.

There was a short-lived show called "Going Deep With David Rees" where the host explores this in a humorous manner.

It's S1E1, I believe it is available on Amazon. You might be able to find excerpts on youtube.

Anyone being successful with some diy Peltier or compressor solution to make big blocks?

I need big blocks, more than my freezer can cope, but not enough to justify couple of thousand EUR worth of machine.

> I need big blocks

I did some searching and at least in my neck of the woods it seems that such blocks can be ordered and delivered. Maybe you don't need to DIY and you can just buy what you need?

Can you justify a few hundred for a big chest freezer and a cooler? Then you can use the cooler method described in this link or in one of the other comments from ir77 on this thread. But just put the cooler inside the big chest freezer.

https://www.alcademics.com/2010/08/a-homemade-giant-crystal-...

It is also terribly slow. I was thinking about something like a cold plate on top of which there is pot of water with insulated sides that freezes from the bottom up - and something to move the water around. so you get constant remelt of the top layer so no impurities.

A second hand ice cream maker could provide the cooling power.

> Hello! If you're heard of directional freezing, learned to make clear ice in a cooler or in a thermos, or purchased clear ice cube trays, that information all came from me, Camper English, writing here on Alcademics.

> My big discovery of what became known as directional freezing was in 2009, and now it's used all over the world in smaller cocktail bars, in homes, and in the form of many commercial ice cube trays (none of which are owned by me, sadly).

Interesting…

Cocktail ice should be formed like a duck, swimming on the beverage.

I had a very expensive old-fashioned once where the bartender chiseled a sphere of ice out of a block. It took about five minutes. The diameter was about 8cm or so.

He created a very spherical sphere. I twizzled it round and round but could not detect any eccentricity. Clearance in the tumbler was even at all orientations.

A carved duck might be more immediately impressive, but the sphere did blow my mind.

It was a very good old-fashioned. I nursed it for 20 minutes - it didn't get watery, as they usually do.

Spheres have less surface area which reduce the watering down of the drink.

Edit: though I would bet that’s less of a factor than the initial temperature of the ice and the liquor.

Almost all of the cooling ice provides is due to melting: the heat capacity of the ice itself (energy release due to temperature change) is much less than the latent heat of fusion (energy release due to melting).

Look at the huge jump at 0 deg C in this diagram: https://upload.wikimedia.org/wikipedia/commons/9/9d/Heat_cap...

It takes less heat to warm ice from -100 C to 0 than it does to melt ice at 0 C to water at 0 C.

Today's your lucky day. There's a guy on YouTube who has been playing around with this at home and various other shapes - https://www.youtube.com/watch?v=tnotAvxKhPY

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