I’m aware of a few different ways to make perfectly clear ice, but each has its own tradeoffs.
I’m also aware of a whole bunch of different ways people claim to be able to make clear ice, but I’ve been unable to replicate.
What are you doing? Does it require special equipment? Do you recommend it?
Methods that don’t work for me:
Filtering: The dissolved gases don’t get filtered out, and will still form bubbles and cloudiness as it freezes.
Vacuum pressure pulling out dissolved gases: I’ve tried this a dozen times, it just doesn’t get all of it out, even if you bring it to a low pressure boil at room temperature. Or new gas is being dissolved in the time between pulling the ice cube tray out of the vacuum and it freezing a few hours later in the freezer.
Filtering won’t get dissolved solids like calcium, magnesium, chloride, etc out, and those will all contribute to nucleation of ice crystals. A bunch of little ice crystals is part of how you end up with cloudy ice because it will mess up the directionality of freezing.
I’ve tried using distilled water to combat this, but it isn’t foolproof by itself without doing one of the other methods.
Edit to add: I’ve also tried boiling water to try to degass it, but it didn’t seem to be effective, either.
For the vacuum pressure pulling, are you doing that in a chamber sealer then freezing the bag?
Yeah I tried it by putting the ice trays directly in the chamber sealer, and then vacuuming it until a bunch of air bubbles out, even to the point of getting it boiling sometimes. Then I’d try to gently transfer it to the freezer. And then get cloudy ice anyway.
I don’t think I’d be able to do it sealed in a bag, because the shape of the vacuum seal bags would compress the ice cube tray into a distorted shape.
What happens if you just put the water in the bag, seal it, and freeze it in a shape? Rods might be easier then blocks, but wonder if it would make clear ice?