Here’s an easy method to make clear ice balls for soft drinks, cocktails, or a whiskey/rocks glass. One ball will keep a drink cool for at least 60 minutes, with minimal dilution compared to ice cubes of equal volume. Plus, it looks incredible in the glass.
The secret is directional freezing — cooling the water in such a way that any air bubbles are pushed out of the ball mold before it fully forms into ice. Normally, ice freezes from the outside in, forcing unseen air bubbles inward until they collect and cloud up in the center. Adding an insulated container, however, provides a reservoir of water that freezes slower than that in the non-insulated mold. This lets the freezing begin at the top of the mold and move downward, pushing air bubbles out into the reservoir instead of trapping them. The result? Crystal clear ice! (Find more on this process by its pioneer, Craig Belon, on the Alcademics site.)
Be a Baller
1. Fill insulated container to the top with bottled spring water. Tap water works too, but in my trials spring water produced the clearest ice.
2. Fill ice ball mold with spring water too (Figure A) and seal with finger.
3. Invert the ball mold (Figure B) and fit it snugly onto the filled container (Figure C).
4. Freeze for 24 hours and remove clear ice ball.
Store your ice balls in a zip-lock baggy until cocktail hour.
Make a Slow-Freeze Jacket
If your freezer is set to 0°F, your ice balls may still form too quickly and show some clouding. You can fix this by making an external insulation sleeve from sill foam (Figure D).
1. Measure and wrap 3 separate layers of foam around the container and ball mold, cutting the pieces at 45° for seamless wrapping.
2. Tape each layer in place, or use spray adhesive (with Goop adhesive on the seams) to make it permanent.
3. Add a cap of sill foam with a hole cut at an angle to expose the very top of the ball mold.
4. Fill mold with water, place on container, then slide the sleeve over the top and place in freezer.
More clear ice ball experiments and techniques can be found on my site.