Category: ice

How to Make Clear Ice, The Hard Way
Darcy over at ArtofDrink.com has taken up pursuit of clear ice. In his first post, he noted something that I did not consider and that could be very helpful.

As the ice increases in thickness it begins to corral all of the impurities into the center of the block. Dissolved air and unfiltered water will cause a cloudy core, but impurities are not the main reason why ice cubes are rarely crystal clear.

This expansion pressure is what makes ice cloudy in the center, not minerals and other debris. The visual flaws are caused by fractures in the ice when the last remaining liquid water in the center of the cube freezes and exerts a massive amount of force on the surrounding ice. The cube is basically cracked from the inside out.

This is in line with what I discovered when I tried all sorts of ways to get the air and impurities out of the ice- in the end it just didn't matter that much.

So in his second experiment, Darcy set about making ice freeze from the bottom up, so that the last part to freeze would be the top. Thus there would be no pressure cracking of the ice. His equipment list was:
- 6 ft of copper pipe
- my wife's cookie sheet
- tin-snips
- a bag of nails
- a garbage bag
- an aquarium pump (powerhead)
- a square garbage can
- a coat hanger
- two Canadian winter days and nights at roughly -10°C
As he noted,

The process works, but it isn’t very efficient nor is it practical.

Anyway, there is still more work to be done. Icesperiments will continue!

An index of ice experiments on Alcademics can be found here.
January 14, 2010
Is Faster Frozen Ice Less Cloudy than Slower Frozen Ice?

In the last installment of my ongoing adventures making clear ice at home in the freezer, I found that using a hard-sided Igloo cooler works pretty well to create large, mostly-clear blocks.

I was curious to see if faster frozen blocks (with the freezer turned to its maximum cold setting) would come out more or less cloudy/clear than blocks frozen at the minimum cold setting.

Of course, my freezer isn't exactly high-tech. According to my novelty jumping bass fish thermometer I picked up in Finland (thanks for the trip, Finlandia!), my freezer only ranges from -3.2 to 2.2 degrees Fahrenheit.

Anyway, as you can see below, there wasn't much difference at all. Here's the block set on the warmest freezer setting (slowest to freeze):

And here at the coldest setting, which froze faster:

My finger (I should be hand model, right?) indicates where I'd cut the block to get rid of the too-cloudy ice. One was 12 cm and the other 12.5. At that difference, you may as well turn the thing all the way up and have your ice sooner.

More icesperiments to come!

An index of all of the ice experiments on Alcademics can be found here.

January 5, 2010
Inside the Freezer of an Ice Nerd

Well I certainly wouldn't want any food in there spoiling the flavor of my ice that I spent so much time making.

January 3, 2010
Clear Ice Blocks at Home in an Igloo Cooler
This post describes how to make a clear block of ice using a picnic cooler. Since I first wrote it in 2009, I have figured out a lot about ice, but this was the defining post for what would become known as "directional freezing." What is Directional Freezing? (the basic theory behind clear ice).

An index of all of the ice experiments on Alcademics can be found here. It's also a great place to start.

Before I figured this out, I tried many other experiments.

Early experiments were:
And I had success with:
- Releasing Air Trapped in Ice
- Cutting Corners to Make Clear Ice
I also learned some ways to cut ice into big chunks.

Now I am trying to refine what I call the Pond Method, the concept that if we freeze water from the top down only (and not outside-in), all the trapped air that makes cloudy ice will be the last to freeze on the bottom of the container, rather than in the middle.

In the last attempt I used a collapsible beer cooler. I had good success in getting clear ice, but found it really hard to get the ice out of a cooler.

This time I tried freezing water in a hard-sided plastic Igloo picnic cooler. Initially I left the cover closed, but after two days it had only barely started to freeze (a good sign for its insulating abilities) so then propped the cover open.

After a few days when the water looked almost completely frozen and I could see some cloudiness forming at the bottom, I removed the cooler from the freezer. I turned the cooler upside-down and waited for the ice block to drop out of the cooler. Presto! It was ready.

There was a little unfrozen water at the bottom of the block (with only about a centimeter of ice covering it). This was easy to drain.

Then I just cut off the bottom cloudy part and had a big chunk. Easy!

Once again, the secret to cutting ice is to score it about a centimeter with a knife or saw, then chip it away with an ice pick and hammer.

Conclusions:
- I'm really surprised the cooler didn't crack after the ice expanded, but maybe it didn't because there was a little unfrozen water remaining.
- This Igloo cooler is a totally workable vessel for making clear ice blocks in my home freezer. Hooray! Luckily it is of a shape that allows for easy removal of the ice block.
Future experiments:
- In this first experiment with the cooler I set the freezer temperature on the lowest setting. I'll see if this matters for clarity or if I can use the high setting for faster freezing.
- I also want to try a disposable Styrofoam cooler (if I can find one this winter) just because there is no worry if it cracks, and this is the most reproducible vessel for other people to try at home.
- I should attempt to find a flexible insulating material that can be made into other shapes, such as a tall and skinny shape (thermos?) that would more easily fit in the freezer and can make smaller cubes.
Here are more clear pictures of the ice pulled out of the cooler with some of it unfrozen, and it after smashing off the unfrozen part.
December 28, 2009
Carving Big (and clear) Ice Cubes

After much experimentation I have found one method to make big clear chunks of ice. That method is to put water in a cooler in the freezer, then chop off the top clear layer. Now the trick was to get this into useful sized cubes for glasses.

*Update 2021: A better post on cutting up clear ice is here.

Starting with the slab of ice (this one about three inches thick),

I used a heated bread knife to score the ice just about 1/8th of an inch,

Then tapped the scratch in several places with an ice pick and found it separated really easily.

And I got the whole thing chopped into long spears.

I use these really long ones in a tall glass

and scored and cut the rest of the spears into big fat cubes.

Hooray! Time for a drink.

An index of all of the ice experiments on Alcademics can be found here.

December 2, 2009
Clear Ice Blocks from the Fridge
In my ongoing experiments trying to make clear ice in the refrigerator, I first tried:
And had success with:
- Releasing Air Trapped in Ice
- Cutting Corners to Make Clear Ice
Then theorized about the pond method.

The next step was testing this pond method (trying to freeze ice from the top-down rather than outside-in). To do this, I needed an insulated container on all sides except for the top. My first attempt was with a collapsible beer cooler:

I filled it with plain tap water and let it freeze for three or four days. The container expanded as it froze so the ice was rather difficult to remove. At the end, the block still didn't completely freeze, but as we've learned in earlier experiments the last parts to freeze are where the ice gets the cloudiest. It was also cloudy toward the center but I think that's because I gave the cooler a squeeze in the fridge before it was frozen.

The next task was to cut off the cloudy parts so that only the clear ice remained. The first time I did this with a saw. This took a long time and as I learned later was probably not necessary.

But it worked!

Part Two: Just a Bit Off the Top

Since I wasted so much of this large block I wanted to try a simpler method: Freezing it from the top down and trying to just pop off the top.

Once again I filled the cooler with water and froze it, for just a couple of days this time. When I pulled it out of the freezer the water had mostly froze from the top down, though there was a light shell of ice around the shape of the cooler. Thus to get the ice out, I smashed in the sides of the cooler and pulled off the top. It was a bit easier than the entire block to remove from the cooler, but not easy per se.

This slab was about four inches thick and wonderfully clear.

The next trick would be trying to cut it down into smaller cubes. More on than in the next post.

Conclusions:
1. To make a big slab of clear ice, start with an even bigger slab of ice and cut off the rest. At least for San Francisco water, the shape of the container matters more than anything else- boiling, filtered, or distilled water.
2. My collapsible cooler isn't heavily insulated, so the water does partially freeze from the bottom and sides and a better insulator would be ideal.
To do:
1. Find a better insulated container to maximize the "pond effect" so that water only freezes from the top down.
2. Figure out how to efficiently cut the ice into big cubes.
An index of ice experiments on Alcademics can be found here.
December 1, 2009
Another Clue to Ice Clarity: Slow Freezing Like a Japanese Pond

The other night a friend of mine told me that she read something about clear ice, which as you may recall is a topic of interest of this blog. Naturally I forgot what she said (we were at a bar, remember) but the next day I found the following email I had sent to myself:

"Clear ice old japan sawdust"

The amazing thing is that when you put that into Google the very first story it comes up with is what I assume is the exact thing my friend was talking about. In this story on natural ice (popsicles) in Japan, a person in the story gives a quote that could prove useful.

Masao Yoshiara, the fourth-generation president of the company, said: "In Nikko, the daily lowest temperature in winter averages around minus 10 C, ideal for making crystal-clear ice.

"If it's colder than that, ice can be made quickly but it is not solid enough. Here, ice grows 1 centimeter thicker a day. When ice becomes about 15 centimeters thick over half a month, we cut out ice blocks. If an ice block is thicker than that, it contains cracks."

Minus 10 degrees Celsius is 14 degrees Fahrenheit. I don't know the temperature of my home freezer, but it's worth investing in a thermometer to find out. Perhaps slow freezing equals clearer ice.

The other factor we'll have to consider about pond ice is that the bottom never freezes. Thus the air that is a major factor in cloudy ice is still in the warmer water below the surface layer of the ice.

This is another strategy I've been considering in attempting to get clear ice in the freezer: if I place a good insulator at the bottom and sides of the water container that doesn't cool down nearly as fast as the water (for example a super thick glass bowl, or a pan of ice that sits on a stone surface), will that cause all the air in the water to migrate to the bottom and freeze last?

This reading inspires a lot more ice experiments to come. I'm glad I emailed myself from the bar.

An index of ice experiments on Alcademics can be found here.

November 19, 2009
Does Freezing Water in Layers Make Clear Ice?
Here's a new edition in my ongoing ice experiments. So far, there experiments have been:
With successes in:
- Releasing Air Trapped in Ice
- Cutting Corners to Make Clear Ice
So far my conclusions have been that (at least with my San Francisco water), temperature and filtering have less of an effect than trapped air that migrates to the center of the freezing cube. Thus I am trying to minimize this effect.

In this experiment I froze ice in layers in small lasagna pans to see if we had a maximized surface area, hopefully no air would get trapped in the ice and form cloudy parts. Apparently some commercial ice machines such as Kold Draft spray an upside-down mist of water in layers, so this would be the home approximation of that.

I tried this experiments with tiny layers, medium layers, and large layers in the same sized pan, the difference being that I added more water per layer. I let the water freeze before adding another layer.

As you can see, none of the layers turned out clear:

(Tiny layers, medium layers, and large layers left to right.)

The small sized layers were made only adding a couple of ounces of water at a time, so I can't get much smaller layers than these unless I use a spray bottle.

We'll have to call this one a failure. Freezing water in layers does not appear to make clear ice, just ice with smaller layers of trapped air.

Below is a closeup of the layers for your ice ogling enjoyment.

An index of all of the ice experiments on Alcademics can be found here.
November 19, 2009
Cutting Corners to Make Clear Ice
In an ongoing set of experiments I've been trying to make clear ice at home. I've tried:
With some success on the last one. While what would be ideal would be to produce one giant solid block of perfectly clear ice, I haven't figured that out yet. However if the ice is going to be used to shake with or for cooling individual beverages, you don't need a giant block- just big chunks.

There is a way to accomplish this by cutting corners. And tops and bottoms. We've seen how the air bubble makes the cloudiest part of the ice in the center in vertically-frozen water, and mostly along the bottom of horizontally-frozen water.

And I've also found that horizontally-frozen water usually has an edge of very clear ice.

So with my ice pick, I just cut off the clear edges separated the top from the cloudy bottom
of the pan ice (easier than you'd expect, as the cloudy ice breaks off easily), and cut around the cloudy middle of vertically-frozen water to end up with a big bowl of clear ice.

Conclusions: You can make clear ice by cutting around cloudy ice frozen in large blocks. However, you waste about 85% of your ice, and a lot of time.

An index of ice experiments on Alcademics can be found here.
October 23, 2009
Making Clear Ice by Releasing Trapped Air
[update: after this post, I figured out the trick to making clear ice – check here for the solution.]

Finally, I've got a minor success in my clear ice experiment to share. So far in an attempt to make perfectly clear ice in my home freezer, I've tried:
Noting that water freezes into ice from the outside-in, leaving an air/water bubble that forms the cloudy part of ice, I sought to devise a way to either change the way ice freezes, or to release the trapped air while the ice was freezing.

First I tried laying a bar spoon diagonally through the water. The theory was that the metal of the spoon might conduct coldness into the center of the ice so that the ice would freeze more evenly. The intended result was a dispersed air throughout the ice rather than just in the bottom/center layer.

But alas, the intended result did not happen. There does appear to be more air dispersed in the ice, but still the majority of it is in a layer along the bottom.

Next I tried inserting a straw into the center of a tray of ice to see if the air would escape through the straw. The plan was flawed to begin with, as water would probably just freeze inside the straw so no air could get out.

In reality the freezing ice pushed the straw up so that it was only inserted about half an inch into the ice by the time it was fully frozen. This had no effect on the amount of cloudiness.

For something that did work, keep reading after the jump.

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October 23, 2009