We already know that you can make perfectly clear ice balls using a round silicone ice mold and an insulated mug.
(Read about all the ice experiments on Alcademics by following the link to the index.)
Now Alcademics reader Jason F. has refined the process using larger Tovolo Sphere Ice Molds and a cooler.
The equipment is specifically the:
If you're new to the ice experiments on Alcademics, it might help to read the top stories linked to from the Index of Ice Experiments on Alcademics.
This ice ball process is similar to the method using the insulated mugs and making ice blocks/cubes in a cooler:
- You fill the ice ball molds with water, and float it hole-facing-down in water in the cooler.
- As the water freezes from the top-down (due to the insulated cooler), it pushes any trapped air and impurities toward the bottom of the cooler, leaving only clear ice in the mold.
Fill the cooler almost full with hot tap water. Allow it to cool for a few hours until it is about body temperature. Separate the molds put them in the water and re-assemble them under water making sure that all of the air is out of them.
Grasp the top and bottom of the mold keeping one finger over the drain hole of the mold. Take it out of the water and dump the water remaining in the white plastic part of the mold.
Place the mold back in the water, hole side down and release your finger from the drain hole on the rubber side of the mold. This will ensure that air has not gotten in and give the top some buoyancy.
Place the cooler in the freezer for 48 hours. The ice will form at about 1 inch per 12 hours. The block will not freeze all the way through and that is exactly how you want it!
When you remove your cooler it will look like this:
Chip away the surrounding ice using the ice pick. Reserve the ice as you will have some nice, clear rocks for other cocktails.
You will get a block out with the molds frozen in it. Work on the shammy or tea towel so it does not slip around.
Remove the sphere from the molds, they will just pop out no need for running water over them.
Tempering The Ice
Allow the spheres to temper (sit out) on the towel for about 10 minutes. Tempering them is an important step so that they don’t crack when liquid is poured over them.
You can store them in the freezer but remember to temper them when you remove them.
When they come out of the mold or freezer they will be dull on the outside. You know they are tempered when they are clear all around.
Thanks much to reader Jason F. for the method, the text, and the pictures!
The index of all ice experiments on Alcademics is here.