Ice cubes in most bars are clear; at home they’re always somewhat “frosted.” Can clear cubes be made at home?
Boil the water first. You might also need distilled water.
A water-filter may also help. Also let the trays sit out either on the counter or the fridge for a while (5 minutes or so) before sticking them in the freezer.
Reasons behind advice:
Tap water has airbubbles and little itty bits of particulate matter in it (that also catch the air) that make them cloudy. Using distilled or boiled water gets rid of those little imperfections, and letting the water sit either lets them settle down, or bubble out, before the water is frozen.
Not guaranteed to work. All my ice is made from filtered water (Brita filter) which has been sitting on the counter for hours. I just looked at the ice cubes in my drink, and they are far from clear. There must be some other factors involved.
This sounds easy enough to try.
Shockingly, this is one area in which I am a minor “expert”.
I made a short video on the subject. Boiling is absolutely not sufficient. The trick is fairly simple but it does take a bit of effort.
The goal of the clear ice was to have good feedstock for another project of mine; an ice ball maker.
This is the explanation I have heard, somewhere: Commercial ice makers freeze the water from the bottom up, by flowing water over a cold surface. Dissolved gases in the freezing water can then escape as the ice is forming. Your freezer probably freezes the cubes “quiescently”, so that a layer of ice forms first on top, trapping the gases as they try to escape from the freezing water below. The gas bubbles leave little trails as they try to force their way out of the solidifying water. The cloudy ice that results is no dirtier than clear ice, assuming that the water was equally clean to begin with. But the clear ice looks better, and frankly, I prefer it too. All water contains dissolved gases, by the way. (I think)
This is pretty close to the right answer. A small correction: the real problem is that household ice is frozen from the outside in. As I showed in my video above, it works equally well to freeze from the top down. As long as there is a region of liquid water to push the bubbles to, you’ll get clear ice. My technique uses a partially insulated container to achieve the effect.
The other thing the commercial units do is have an insulated but non refrigerated bin so that frost cannot collect.
Cool - I wish I had seen that a few months ago when I was trying to do this, but I kept seeing all the recommendations for boiled, distilled, and filtered water. I tried even boiling distilled water. It may have made a difference, but we are talking say if 100 was regular - and 0 was perfectly clear - I’d rate the block you made as a - I don’t know - a 3 - due to those small bubbles, the cubes I was making never got below a 95 or so.
I gave up as I had tried eight or so batches and never saw any (significant) improvement.
:). I’ve made blocks that would rate a “0”–mainly it just takes a bit of extra time sitting in the open to de-aerate a bit more. However, I usually don’t try very hard since I think the level of bubbles you see gives it a bit of character, like you might see in a glass paperweight. I’ve been meaning to experiment with an ultrasonic cleaner, which I’ve found does a good job at de-aeration.
I also spent a great deal of time on boiled/distilled/etc. water and found the same thing you did. It made a small difference, but not enough to be worth it, and not enough that you could say you’ve really got clear ice.
I made a quad unit so that I could prep slugs fairly quickly for a party. A week of prep is generally enough so that everyone can have one or two, and although the freezing takes a while, the actual effort is pretty small.
Yeah - I was doing this layered cocktail drink think - with a special glass - special straws - special ice cube shape - and then realized the ice was all cloudy. I started to get a little OCD about it - and really couldn’t justify the effort and say
“look how clear the ice is”
“Looks the same to me”
“No it’s not - look at this one - clearly there is maybe 5% less cloudiness”
So is used the cloudy cubes - and it was pretty impressive anyway - and the drink ended up being less clear than I had intended - so it didn’t matter as much.
I had read that blowing air over the ice (while freezing) - or vibrating the ice (while freezing) - might help. I had little faith (nor an easy way to do that without spending even more time & money on this). At least you have a video - so I know your method works! I don’t think I could have gotten the shape I wanted though, but oh well.
I see we think alike. I also wanted my ice ball maker to have perfectly clear ice. I would see pics like this and think “You spent a grand on your ice ball maker to get ice balls that looked like that? Rubbish!” So I researched how to do it myself and found a guy that recommends using an insulating cooler in the freezer; that didn’t quite work for me since I wanted smaller blocks, and a cooler wouldn’t have fit anyway, so I came up with this system.
In fact, normal, non-OCD people do appreciate the difference. We’re used to having cloudy ice at home and the clear stuff really stands out.
The ice balls are actually pretty cool looking in opaque drinks, since you can peer into them like a hole.
Not to be a spoil-sport, but this is really simple. Filters, distilling, boiling etc. = waste of time. This is not how commercial ice machines make clear ice. They do it by using constantly flowing water which allows for regular, clear ice crystals to form. Simple as that. You want to have consistently clear ice cubes? Either buy commercially made ice or invest in a commercial ice machine. Given how expensive they are this is not a practical option for anybody. Just get used to your cloudy ice… 
Nope. See post 6. About $4 in materials.
The technique works better for larger blocks than cubes. That’s ok; smash the blocks with a hammer and you get elegant, irregular ice chunks.
Yeah, people who make ice for professional ice sculptures say they get it clear by keeping the water moving, while it’s freezing. I know because I used to work a lot of corporate events with huge ice sculptures, though I was mostly using the Martini luge!
Sparge the water with argon prior to freezing. Or try several freeze-pump-thaw cycles prior to freezing.
Spoken like a true Old Money elitist who has their own private sparge sitting around.
I MAY have a neighbor who I can borrow some argon from; he borrowed some brown sugar from me last summer, so he owes me, but I can assure you that us 99%ers don’t have the means to keep and maintain our own personal sparge, if we even wanted to.
Snob.
If the problem is air bubbles, wouldn’t a cheap vacuum pump do the job? http://www.amazon.com/GSC-Vacuum-Pump-Hand-Operated/dp/B001DBOUOC
Your video is confusing because you show a plastic glass and a pitcher, you make a mold around the pitcher, but later you switch the pitcher and its mold without comment for the plastic glass and its mold. An annotation, at least, would seem to be a good idea.
In blind taste tests . . .