Tag: how to make clear ice

Using Salt Walter as an Insulator to Make Clear Ice

This blog post is a continuation of this experiment.

In this experiment, I wanted to test out another way to insulate an ice cube tray to make clear ice. Inspired by a comment from another blog entry by a reader named Gael, I decided to try salt water as an insulator rather than just plain water as in the last experiment. If it worked, this would be a way to make clear ice at home without taking up too much freezer space.

I took a small food container and put it into a slightly larger one. The smaller container held only water. The outer container held water with table salt. The theory is that the salt water would not freeze, so it would act as an insulator for the ice, and control the direction of freezing so that it would only freeze from the top-down (as with the cooler method).

I didn't use a ton of salt. As you can see, the outer container's water did freeze lightly,though it was soft. The bottom did not completely freeze, as you can sort of see here.

The inner container did seem to freeze toward the bottom.

In better-insulated containers, the cloudy part is only on the bottom of the container. Here, it is concentrated but raised slightly above the bottom of the container.

In this case the inner container sat directly on the bottom of the outer container, so it wasn't greatly insulated on the bottom. My theory is that this is why the cloudy part of the ice is raised above the bottom.

To improve this experiment, I would put raise the inner container off the bottom of the outer container, and probably use a greater amount of salt in the salt water.

As the outer container here is only slightly larger than the inner container, this system is more space-efficient than the Igloo cooler for many people without large freezers.

There's more work to do on this…

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

October 26, 2010
Making Crystal Clear Ice in Wired Magazine

Run screaming to the newsstand to pick up the June issue of Wired magazine, because there is a story by me in it. Sure it's only 100 words long and it's about how to make clear ice, something you may have read about here, but you can consider it a collector's item.

Update: The article is online here.

May 25, 2010
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
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