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Comment by pmx | Hacker News Reader

it's actually much easier than this makes out. Sodastream bottle, some kind of cloth like a tea towel, pillowcase or even a sock over the end, let 'er rip and you have a chunk of dry ice.

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That’s cheating! You outsourced the pressurization step. :)

indeed! I also don't dig my own well every time i wish to boil water for tea!

You're supposed to just dig the well once.

Relying on past me is cheating. Current me needs to finish it all in one go.

“If you wish to make an apple pie from scratch, you must first invent the universe”

-- Carl Sagan

rating: 2 stars

I substituted brown sugar for primordial quarks, and I used an air fryer instead of a big bang. apple pie came out mushy and bland.

Done this with 10lb CO2 containers used for brewing and such. Really doesn't take much CO2 to make a good amount of dry ice.

At that point, why not just buy the dry ice directly? It would surely be cheaper...

I have never seen plain dry ice for sale anywhere, though I have not gone looking too hard. I have seen the dumping some liquid CO2 into a special sock method though.

I see it in supermarkets, often kept by the customer service counter.

I've seen several places requiring ID to purchase dry-ice to avoid youngsters making soda-bottle bombs with it.

It's dangerous enough (suffocation, freezing) that there are plenty of reasons to require an age minimum. I don't think I've seen dry-ice in supermarkets since COVID started, but I haven't been looking much either.

Never disappeared around here. A lot of people rely on it to get their frozen stuff home without thawing out. So it's more available in rural places where people will have a long drive home.

Ahhh, that makes a ton more sense now. As one of the aforementioned soda-bottle-bomb-making-youngsters, I had no idea what people's legitimate uses for it were outside of party tricks.

I buy it on camping trips. It has a major benefit of not getting your stuff wet as it melts.

All of the stores in my area require you to be 18 and produce ID to prove it, yes.

They often don’t advertise its availability but most grocery stores in the US do sell it.

It’s very useful for road trips, power outages, and shipping perishable items.

This kind of depends on the location/jurisdiction. The more rural you go, the more likely you can buy it. In a lot of big metro areas you'd be better advised to call ahead until you find a store that carries it.

On Halloween, my grandma (I’m in the US) would dress like a witch and use dry ice carbonate homemade root beer she’d dole out to kids from a giant bubbling black cauldron. I thought grandma was an actual witch for a while there.

homemade root beer is pretty difficult to do well!

I think all my local grocery stores sell it and so do at least some of the ice cream shops. None of them really advertise this; you just have to ask for it at the cashier.

This may be a dumb question, but how do grocery stores store the dry ice they intend to sell? This stuff has to be kept very cold to prevent it from sublimating. Do they just keep it in an insulated box with a vent and just accept that they will loose some of it?

> Do they just keep it in an insulated box with a vent and just accept that they will loose some of it?

This is what the stores near me do, yes (they're actually freezers, but certainly not ones that reach dry ice temperatures). I don't know if they have a separate storage location they use overnight while the store is closed, but I suspect not.

Yea it just vents. This might seem odd but it’s cheaper than maintaining a cryogenic cooling system. Very well insulated containers are cheap and heat gain only occurs along a surface where they’re storing a large volume. So losses per day end up being trivial when they’re only paying ~0.5$/pound and selling it for 3$/pound.

Honest question - where do hell people buy dry ice from like it's the easiest thing ever, I've looked into it and there was no one within hundreds of miles from me who would sell to private buyers. UK here.

Here in the US, you can buy it at the supermarket.

I've had trouble finding it in NYC; my initial idea for doing SodaStream refills was to simply buy the appropriate weight of dry ice and fill the canister by unscrewing the top, but I wasn't able to find any dry ice available for purchase.

For those curious, I ended up finding a welding supply store that just sold pure CO2 in a tank.

US here. the large supermarket chains (Safeway) stock it as a normal commodity, in the front, next to the water ice.

Or https://www.dryicedelivered.com/ I wonder if they pack it in dry ice to keep it cold while it ships?

Edit: They do.

I once had to find some for the sixth form Physics labs where I was temping.

Chemistry lab at Newcastle University had a freezer full that they were happy to share from.

Theatrical suppliers may help too.

As an American I had the same expectation trying to buy dry ice in New Zealand - couldn't find it in supermarkets or petrol stations. I wanted to get some for our outdoor/off grid wedding to keep the beverages cold for several days. Eventually I called BOC (who supply industry and hospitals) and they agreed to sell us some but when I showed up with a cooler (chilly bin) they laughed at the tiny amount I wanted and filled it up. I don't think they'd ever sold it like that to a private buyer.

In the US some supermarkets have it for sale. Most do not that I've seen, but I know a few who carry it in stock.

All the stores near me sell it.

Here in Canada, it's companies like Praxair or Air Liquide. Major centres will typically have one, maybe a 10 pound minimum for dry ice.

Well, one reason is that you can store CO2 in a tank for a long time, in lots of conditions, easily and with basically no cost. So, if either A) no stores convenient to you sell it or you need it at more flexible times etc, or for some other reason you want to it on demand at a price premium, it could be worthwhile.

But, based on the write-up here, it sounds like he was doing this out of curiosity, at which point yes buying the CO2 would sort of defeat the point.

Of course, one could also ask the same questions about buying the baking soda and acid. There is no clear delineation at which point before which it's "made from scratch" vs. "store bought".

Sounds like the answer in this case was: the person in question thought that starting from purchased baking soda and acid was an interesting problem to solve, and starting from bottled CO2 was a boring problem to solve and starting from some precursor to baking soda and acid was too much of a pain to solve.

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