Alcademics

Update: Learn more about this in The Ice Book, out May 2023!

Did you receive one of those cool Star Wars Death Star ice molds as a gift (or buy one for yourself), only to have it come out looking not like the advertisement:

Image from the ad on Amazon.

But more like this?

Yeah, more like post-Skywalker Death Star. 

Don't worry, I have a fix for you. The trick is take advantage of Directional Freezing, a technique I pioneered here on Alcademics.com. 

In a nutshell, the regular way ice ball will freeze is from the outside-in. The ice "wants" to be clear in a nice neat organized lattice so it pushes trapped air into the center of the ball, where it appears cloudy and also cracks as it expands. With Directional Freezing, we make sure the ice ball freezes from the top to the bottom, pushing that trapped air out the hole in the bottom. 

We accomplish this by using a Thermos Funtainer (or other similar insulated mug, but this one fits the 2.5" ice ball molds perfectly and takes up the least amount of space in your freezer). 

1. Fill the Thermos with water
2. Fill the Death Star ice ball mold with water (I use water from a Britta filter)
3. Hold your thumb over the hole in the Star Wars ice ball mold and turn it upside down, setting it on the Thermos with the hole facing into the thermos. 
4. Put it in the freezer and wait 12 20 hours or so for it to freeze, depending on your freezer. 

The ball should now be super clear. 

Common issues are that it comes out more egg-shaped or that it's a touch cloudy on the last part to freeze (where the hole is). If you're experiencing that, try:

• Move it so that the hole is either directly down in the center of the thermos, or a little on an angle towards one side (depending on if your freezer is excessively cold or warm)
• Beware excessive vibration/jostling the container in your freezer, usually caused by opening and closing the door a lot. This can cause bubbles and stop the directional freezing process. 
• Some super-obsessed Alcademics readers claim that to get every last cloudy bit out of the ice ball (often the last part to freeze is slightly 'frosty' in appearance), use bottled water. We haven't figured out why this would make any difference, but they claim it does. 
• Most sink faucets have a aerator on them - even if your water doesn't need to be filtered, letting it sit a while or removing the aerator can help if the ice is still cloudy and freezes fast. 

Enjoy your super clear Star Wars Death Star ice balls, and may the force of Directional Freezing be with you.

To see all the many, many ice experiments on Alcademics, follow this link to the Index of Ice Experiments.