Making dry ice at home

I tried to make a TEC chip dry ice maker. It was hard to manage all the heat the TECs made. I ended up with an elaborate water cooled device with a large copper block acting as a thermal mass interfacing with a TEC tower and 3d printed insulated chambers etc. I got a little bit to freeze, and I could get temperatures close to freezing nitrogen, but eventually my wife made me clean up my huge mess in the dining room.

Our chem lab in high school (in the 80s) had a CO₂ tank attached to a metal cylinder similar to the 3D printed one shown here. You just hooked it up and turned on the valve to create a puck of dry ice. So if you need it frequently and have trouble finding it for sale, maybe look for the modern equivalent.<p>(It being high school, about 5% of the dry ice created was used for legitimate chemistry purposes.)

My FAVORITE thing to do with dry ice is make ice cream. It’s the smoothest ice cream you can make at home, and as a delightful bonus, it’s fizzy!<p>You have to crush the dry ice into graupel size (even better, into snow) for it to be safe, and it can be super messy if you add the dry ice too quickly. It’s important to make the pieces as small as possible to ensure they fully sublimate, and no dry ice is remaining in the mixture where it could be ingested. Frostbitten tongues are terrible; frostbitten stomachs are a threat to life.<p>Just start with a normal ice cream base in a large mixing bowl. If you have a stand mixer with a blade suitable for ice cream, that’s even better. Slowly (or there’ll be a big mess) add crushed&#x2F;pulverized dry ice while mixing. Keep going until the ice cream is stiffer than soft-serve, but not so hard that you can’t mix it any more.<p>It’s colder than normal ice cream, so eat small mouthfuls. But damn, it’s got an indescribable &#x2F;zing&#x2F; from the little bit of CO2 that dissolves into solution with ice cream base. SO GOOD.

Dry ice has become really quite scarce in the last five years. It was explained to me at the ice shop I used to visit that there were changes in some shipping regulations, not too sensible ones, that resulted in a much higher price and a bunch of people just dropping out of the business. Indeed, that place finally got out of the dry ice business as well.<p>Airgas has some pretty tight hours and in smaller towns, they don&#x27;t even have it stock. Penguin supposedly has it in different places like Walmart but it is a complete gamble. Local grocery stores have bailed out. I&#x27;ve had no luck at ice cream places.

it&#x27;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 &#x27;er rip and you have a chunk of dry ice.