In an ongoing set of experiments I've been trying to make clear ice at home. I've tried:
- Distilled vs. Tap Water
- Melting and refreezing water
- Hot Water vs. Cold Water
- Carbonated Water vs. Still Water
- Horizontal vs. Vertical Container Shapes
- Releasing Air Trapped in Ice
With some success on the last one. While what would be ideal would be to produce one giant solid block of perfectly clear ice, I haven't figured that out yet. However if the ice is going to be used to shake with or for cooling individual beverages, you don't need a giant block- just big chunks.
There is a way to accomplish this by cutting corners. And tops and bottoms. We've seen how the air bubble makes the cloudiest part of the ice in the center in vertically-frozen water, and mostly along the bottom of horizontally-frozen water.
And I've also found that horizontally-frozen water usually has an edge of very clear ice.
So with my ice pick, I just cut off the clear edges separated the top from the cloudy bottom
of the pan ice (easier than you'd expect, as the cloudy ice breaks off easily), and cut around the cloudy middle of vertically-frozen water to end up with a big bowl of clear ice.
Conclusions: You can make clear ice by cutting around cloudy ice frozen in large blocks. However, you waste about 85% of your ice, and a lot of time.