I want to make some ice cubes that are large (1" on a side or more), crystal clear, and perfectly cubical. I want them large to make my drinks dilute less slowly, and clear and cubical because I think it looks nice. When I make ice in the freezer, it's always cloudy. Any ideas?
The cloudiness is caused primarily by impurities. Use distilled water and boil it twice, letting it cool between each boil. This removes all impurities and will result in clear ice. The second boil may be unnecessary, but it can't hurt. Make sure you keep the pot covered while it cools.
Wired Magazine had a recent guide on how to make crystal clear ice. I'm copying it here since the article says it's under Creative Commons license:
Go Big Ditch the ice tray and use a large vessel like a thick plastic bowl or, better yet, an insulated cooler. Fill it with water and stow it in the freezer.
Wait The H2O can take a day or so to solidify. Remove the mini berg when it’s solid on the outside but still has a liquid core.
Drain With an ice pick, bread knife, or screwdriver, make a hole to release the trapped water.
Segment Score a grid onto the slab of ice, then pry it apart into cubes - the ice should break cleanly along the seams. Bigger cubes are ideal because they melt more slowly.
Contributed by Camper English
Another way to remove impurities from water is to just let it sit. Fill a bowl with water and cover it. Come back a day later and ladel the water from the top.
Impurities tend to sink to the bottom, but it takes quite a long time.
try breaking the crystals every time they begin to set. once you have the start rebreak the cubes. this will also remove any air bubbles which can cause the cloudiness.
Dave Arnold says that ice must freeze from the bottom to be clear.
I hooked up a Reverse Osmosis system to my fridge and now the ice is clear except for some air bubbles. If I wanted to make some "party ice" I'd use RO water but I would let it sit out for a while before putting it in the freezer to get rid of the air bubbles.
The cloudiness comes from air in the water. Unscrew the aerator from your faucet before filling your container.
I see there's a checkmark, but just as a possible option - if you're talking about non-alcoholic drinks, what about making ice cubes of the same liquid - like some people do with lemonade ice cubes? They still might be visible, but you'd certainly have less dilution.
I believe the trick that commercial ice makers use to make clear ice is to constantly agitate the ice while it freezes.