Clear Ice Blocks at Home in an Igloo Cooler

This is another in an ongoing set of experiments trying to make big, clear ice cubes at home.

Early experiments were:

• Distilled vs. Tap Water
• Melting and refreezing water
• Hot Water vs. Cold Water
• Carbonated Water vs. Still Water
• Horizontal vs. Vertical Container Shapes
• Freezing water in Layers

And I had success with:

• Releasing Air Trapped in Ice
• Cutting Corners to Make Clear Ice
• Freezing Water in a Cooler to Imitate an Ice Pond

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 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.