
A Liquid Nitrogen Cocktail Party - RKoutnik
http://sockpuppet.org/blog/2015/01/13/liquid-nitrogen-cocktail-party/
======
tptacek
Summing up a bunch of comments, rather than littering the thread:

* There is no LN present in the final product. LN is literally nitrogen in liquid state, and nitrogen is gaseous at sane temperatures. You add it in relatively small amounts, and it evaporates away. It is absolutely not safe to consume LN.

* Yes: you need to ask your LN supplier if the LN is food-safe. This is an easier thing to verify than that a _dewar_ is food-safe (because who knows where it's been). Our LN source also sourced other culinary applications.

* As I said in the post: guests didn't get to handle LN, which is good, because guests were intoxicated.

* The nitro-muddling technique in L.I. is designed in multiple stages to prevent that from ever happening; for instance, if you shake a drink with LN still in it, you'll hurt yourself before you manage to serve a guest LN. The final product has to be pourable. In fact, LN isn't a component of the drink itself, which is chilled with plain 'ol ice (for the dilutive effect).

* The ice cream recipe is freezing cream and egg and sugar, which are all eminently freezable substances (ie: they start freezing at a relatively high temperature). You drizzle LN into the bowl slowly while slowly running the mixer, and you stop when the mixer starts straining against the ice cream. You're never dumping so much LN into the container that it could settle without fogging the whole bowl up (if you do that, you end up with ice cubes instead of ice cream), so it's obvious when it's evaporated off. We remove the ice cream from the bowl with a silicone spatula, to give you an idea of how frozen (or in this case not frozen) the final product is.

( _If it helps you understand, without having had the experience of actually
doing it yourself: the first couple doses of LN into the mixing bowl are
"eaten" by the custard base, which is still liquid. The bowl starts looking
like a smoke machine. You wait for it to clear, so you can actually see what's
going on in the bowl. You repeat until the mixer paddle starts leaving trails
on the bottom of the bowl. Your intuition is that there could be actual liquid
LN in the bowl, but that's not really how it works._)

* An example of an idea that freaked me out and I refused to let happen in my house: people freezing garnishes in LN and adding them to drinks. One of the clearest safety indicators you get with this stuff is "the product you're chilling isn't completely solid" (or, in the case of a drink, "at all solidified or slushy").

~~~
jeffwass
Cool stuff. I used to 'play' regularly with LN2 and LHe back in my grad
student days (experimental condensed matter physics).

I'm curious how much you paid for the 20 liter dewar. Here in London, just
renting a dewar as a one-off and filling with culinary-grade LN2 was amazingly
expensive (several hundred pounds). I wanted to do some LN2 demos and also LN2
ice cream at my daughters' party, but instead opted for much simpler and
cheaper (and less fun) dry ice.

~~~
tptacek
In the vicinity of $500.

~~~
jeffwass
Yikes!

But at least, as you mention, you can be sure it was clean. There's no knowing
what nasties a used dewar might have been contaminated with (heavy metals,
scary organics, etc).

------
mrjones
Interesting fact about liquid nitrogen (that I learned from Dave Arnold's
book, which is fantastic): liquid nitrogen is ~700x denser than gaseous
nitrogen.

So, if you vaporize a moderate amount of liquid in a contained space (e.g.
spilling a dewar in a car or elevator): even if you manage to avoid touching
the nitrogen itself, the gas can crowd out the oxygen and you can asphyxiate
yourself. Since it's odorless and colorless, you probably wouldn't even
notice.

So ... if you do try this at home, be especially careful when transporting
nitrogen!!

~~~
jeffwass
>>liquid nitrogen is ~700x denser than gaseous nitrogen.

One of the coolest LN2 tricks we used to do at our physics demo days took
advantage of this - making bubbles the 'fun way'. Take a big pot of boiling
water and add some dish soap. Wearing your protective gear, dump a few liters
of LN2 into the water/soap mixture, and see it explosively create 700x its
volume in bubbles!

Here's someone doing something similar (he uses room-temp water, not hot, so
the bubbles come out 'frozen')
[https://www.youtube.com/watch?v=X5ZAoHxhihU](https://www.youtube.com/watch?v=X5ZAoHxhihU)

On your comment about displacing air - in my actual research (when we weren't
making LN2 bubbles) we used alot of Liquid Helium (for reference, LN2 at 77K
is about 1/4th room temperature, while LHe at 4.2K is 1/70th room
temperature). We'd often have superconducting magnet running with fields up to
10T, which IIRC required nearly 100A of current in the freakishly-thin
superconducting magnet wire which was submerged in the bottom of the LHe bath
in the cryostat. It's possible that the magnet could 'quench' where part of it
goes 'normal', immediately heating up due to the huge current, causing more of
the magnet to go normal, causing more heating, which eventually boils off all
the LHe, releasing HUGE quantities of He gas into the room. Even something
simple like transferring LHe from the storage dewar to our cryostat, or
cooling down a cryostat the first time, releases huge amount of He gas into
the room. I was glad we had an oxygen meter in the lab (which I demanded our
adviser buy, she didn't want to waste the money on it at first).

------
fractallyte
The article warns about the possible hazards, but it's worth reiterating:
[http://www.theguardian.com/uk/2012/oct/08/teenager-
stomach-l...](http://www.theguardian.com/uk/2012/oct/08/teenager-stomach-
liquid-nitrogen-cocktail)

~~~
tptacek
That person consumed actual liquid nitrogen. The cardinal rule of culinary
liquid nitrogen: don't ever serve a guest liquid nitrogen.

The nitro-muddling technique in L.I. is designed in multiple stages to prevent
that from ever happening; for instance, if you shake a drink with LN still in
it, you'll hurt yourself before you manage to serve a guest LN.

You're not wrong, though. You need to know what you're doing or you can hurt
people. It's for that reason that we actually didn't play around with the
stuff (freezing random stuff and shattering it, for instance); we just
followed processes we knew would work.

~~~
jere
I feel really dense asking this, but I don't have the faintest idea how the
procedures you've mentioned prevent consumption of liquid nitrogen.

When chilling a glass, you dump out the LN. OK. That makes some sense. But
then when making ice cream, you put LN directly into the bowl while mixing.
Huh?

edit: I can see why you don't want to provide too many details. I will just
say this story, while very interesting, terrified me.

~~~
mattmaroon
I have seen stands at local fairs that make LN ice cream to order. It's pretty
neat. I haven't done it, but they have 16 year olds doing it presumably
without incident.

~~~
cafard
There is a stand at the Mount Pleasant Farmers Market in Washington, DC, that
does LN ice cream. I've never tried it--partly because I don't eat much ice
cream, partly because I don't see the point.

~~~
mattmaroon
It's a better method of freezing than traditional ice cream makers. Faster
freeze = smaller ice crystals = creamier mouthfeel.

It's also easier in many ways for them. You don't even have to have freezers,
since you're spot freezing everything. It saves you from buying a batch
freezer for making it, which is $30,000 used. I'm told that if you're buying
LN regularly, the distributor will hook you up with the tank at a low monthly
fee. So it's probably much cheaper to start a stand that way.

The downside is it's a little less time-efficient. It's REALLY easy to make a
5 gallon batch of ice cream in a Carpigiani.

------
car
Liquid nitrogen can be made on site from the ~80% nitrogen in air. Saw this
cool machine at "the" physics show this weekend:
[http://www.elan2.com/product_elan2office.asp](http://www.elan2.com/product_elan2office.asp).
Probably not exactly cheap, but great for medical offices and others who need
a regular supply of the stuff.

~~~
teraflop
Looks like it'll run you about $10k, which is honestly cheaper than I
expected.

[http://show.aad.org/annual11/Data/EC/Event/Exhibitors/152/pr...](http://show.aad.org/annual11/Data/EC/Event/Exhibitors/152/productBrochure3.pdf)

------
batbomb
Not enough good is being said about Cooking Issues and Dave Arnold in the
comments on HN.

If you don't know the podcast, then you've got about 160 hours of catching up
to do. Dave is a better hacker than you.

~~~
MegaDeKay
Exactly. And the Searzall proves it.
[https://www.kickstarter.com/projects/1708738346/the-
searzall](https://www.kickstarter.com/projects/1708738346/the-searzall)

Dave is also more entertaining than you.

------
wooster
For anybody thinking of doing this, finding someone who has (serious, lab-
setting) experience handling LN2 and can personally supervise would be a
really good idea.

~~~
jfoutz
I second this. I've had LN ice cream and it was delicious. The process was
fun, and no one got hurt. Unfortunately, i think that was more due to luck
than to having a protocol for handling the stuff.

~~~
yebyen
Some of my friends from Computer Science House (a terrific organization, btw)
have several times annually LN₂ parties where ice cream is made. I have never
handled the nitrogen myself but I also can confirm, ice cream made with Liquid
Nitrogen is incredibly delicious and probably some of the smoothest ice cream
I've ever eaten. Not to mention it's very fun to watch it being made.

They do have protocols for handling the stuff, there is always a master of
ceremony who is well versed in the process and various modes of failure, and
nobody is ever imbibing at these parties (at least not to your knowledge).

I probably shouldn't talk about the cardboard boat making competition and the
second part of the competition with depth charges made with liquid nitrogen
and soda bottles, but ... oops. You all didn't hear that. Now I'm going on a
watch-list for sure, aren't I.

------
jwcacces
__ Safety Note __

If you store LN in a thermos with a cap that seals the thermos, you've made a
time bomb, and thermos shrapnel does not improve the flavor of cocktails.

~~~
jeffwass
Also remember - any dewar itself, improperly handled, can be a bomb! One
professor I worked for hammered this concept into us when we started work in
his lab.

Yet my PhD adviser did not. Sometime after I graduated, one of my fellow grad
students blew up a dewar!! (Luckily no one got hurt).

He obtained an old dewar from another lab, and went through the usual cool-
down procedure - evacuate the Outer Vacuum Chamber, fill the LN2 shroud, then
pre-cool the main bath with LN2. Stupidly he did not notice there were no
pressure relief safety valves!!! (Not only should you verify these exist, but
you should also verify they work by slightly pressurizing the dewar.) He put
in a bunch of LN2, capped it, and left for the weekend. When he came back, the
dewar had exploded, pretty much along the weld seams, strewing the metal body
and super-insulation all over the lab.

The first professor I mentioned above made sure we understood all valves and
release valves. And also noted that if opened for too long while full with
LHe, it's possible ice could form in the dewar neck, below the safety relief
valves. Always kept me on my toes while working with LHe (well, that and the
fact that LHe burns way worse the LN2 if it makes accidental skin contact).

~~~
tptacek
The dewar I bought from Amazon isn't pressurized. It is literally a big
thermos. I assume it loses more LN to the atmosphere than a pressurized dewar;
on the other hand, the explosion risk isn't big.

~~~
jeffwass
Hmm, does the cap screw on tight like a normal thermos? Maybe it's designed to
always have a loose cap for venting.

The dewars I was talking about above hold several hundred liters, are about
5-8 feet tall, and primarily for liquid helium (where evaporation is way more
of a factor.

The pressure relief valves were built in to the storage dewar's we would get
from LN2 and LHe suppliers, but I don't think the cryostats in our lab had
them built in, you needed to add them separately by connecting onto the
dewar's main flange. The one my colleague exploded didn't have the extra valve
hardware attached, and he just capped it and walked away.

~~~
mechanical_fish
The non-pressurized LN dewars I've seen had a "plug" that was just a cylinder
of foam that slid into the neck of the dewar, with a light plastic cap on top.
It was lightweight enough to bob upward at the slightest pressure, releasing
gas. It probably had a design with channels such that the lip never sealed
completely anyway.

They could easily preserve LN for days. Dewars are impressive.

~~~
tptacek
_Static hold time: 100 days. Evaporation rate: 0.20 liters / per day. 2.25"
Necktube inside diameter. 15" Outside diameter. 25.50" Overall height. Empty
weight: 23 lbs. Full weight: 60 lbs._

:)

~~~
mechanical_fish
Wow, I forgot just how many days that was, I see. Though I now remember that
one of my labs had a storage dewar full of precious biological samples that
was a bigger version of this design, and we only refilled it a couple times a
month.

$500, eh? Hmmmmmmmmmmmmm.

~~~
tptacek
I felt bad about the purchase before we actually used it, but now I'm feeling
like it made at least as much sense as the circulator did as a purchase.
Malort ice cream!

------
refurb
The other thing I would worry about is the source of the liquid nitrogen. If
you're actively adding LN to something you consume, I'd want to make sure I
knew what was in it. I have a feeling that the LN suppliers for welding don't
care if nasty stuff gets in their LN (stored in an unclean container).

~~~
VLM
A long time ago in a galaxy far far away I got to screw around with LN dewars
for waveguide pressurization and also extremely high power coax feedline
pressurization. You want about 2 or so PSI (varies by system) to keep water
out and eliminate all chance of corrosion. The density of liq N2 is such that
a small liq tank is the equivalent of a staggeringly large gas N2
pressurization system like the size of a tank car. Also its very hard to
explode a liq tank and very easy to explode an ultra high pressure tank by
making a mistake with regulators and pipes. A dewar would keep a feedline
pressurized for, eh, maybe week, maybe weeks. Some dewars have a better or
worse vacuum than others. Boys will be boys and we screwed around with the liq
N2 a little. The author got ripped off because in bulk we paid roughly "milk"
prices. Supposedly the liq N2 and milk price comparison held for decades at a
time in the old days. So his little 20 liter dewar should have cost maybe $20
to fill. Then again, higher energy costs than the 90s, liability insurance,
and "we know foodies will pay anything, so lets charge them anything..."

Anyway. Although superficially it sounds shocking that a welding supplier
would certify their product as food safe, all their gasses are designed for
welding, like welding stainless steel food processing gear. So its safe enough
to use anything they sell for industrial use, you'll be OK. If you think
they're scared of giving you cooties, they're much more terrified of causing a
dairy plant to loose its license. Its clean stuff. Also, they're terrified you
or they will "cross the streams" with a O2 supply causing a huge explosion if
there's any grease or oil contamination, so you can be absolutely sure nothing
oily or burnable ever came near the gear, don't even worry about that class of
contaminant. If you think about it, flooding something with N2 specifically to
prevent chemical reactions means its not fit for sale unless its ridiculously
pure. So it is.

Another chemistry problem is you're looking for something that could end up in
the product stream without being filtered out or destroyed by the process gear
(or destroying the process gear), so kryptonite is kinda unlikely. Also it has
to be liq at liq n2 temps because a gas would blow away and a solid (dirty
ice, lets say) would remain stuck to the container. Good luck finding a
substance like that. I'm pretty much out of chemistry ideas for a food
contaminant.

~~~
tptacek
We got price quotes without telling them the application, so I'm pretty sure
we're not paying a "foodie" price, but rather a "you're using a super small
dewar and so effectively pay way more" penalty.

------
jastanton
Dumb question. When you're making ice-cream / drinks are you actually mixing
liquid nitrogen as an ingredient into these drinks / foods? I thought it was
solely an agent to quickly cool things I wasn't aware you were actually
ingesting liquid nitrogen. Does it modify the taste at all? Is it safe?

~~~
Pxtl
Don't think of it as an ingredient, think of it as "frozen air". Literally,
air so cold that it has frozen. That's extrmeley dangerous because it's cold
enough to damage your body very very quickly... but at the same time, when it
thaws over time?

It's air.

Just like how when you cook things, you often use "burning air". If you eat
something burning? You will destroy your insides. The difference is that
freakishly-destructive levels of cold don't ruin food nearly as fast as
freakishly-destructive levels of hot. If we blasted your food with a rocket-
engine, it would be too hot to eat, but it would also be charcoal. If we
blasted your food with liquid nitrogen, it would still look like food and
would still be edible after it returns to normal temperature, so there'd be
more temptation to try to eat it while it's still lethally cold. Hence the
danger.

------
js2
[http://www.nicecreamfactory.com/](http://www.nicecreamfactory.com/) in
Arlington, VA makes very good ice cream using LN and KitchenAid mixers. I was
actually surprised how casual they are about handling the LN. I don't recall
the person who made mine wearing eye protection, but maybe I'm misremembering.

------
IgorPartola
There are lots of videos designed to impress on you the dangers of liquid
nitrogen. I like this one:
[https://youtube.com/watch?v=Ldgp3Ton7R4](https://youtube.com/watch?v=Ldgp3Ton7R4).

It is a really fun thing to play with, and can even clean your floors, but
just like firecrackers, do not contain it.

------
knicholes
This article is simply cromulent.

------
eatbuckyballs
[http://www.marketpavilion.com/nitrotini.cfm](http://www.marketpavilion.com/nitrotini.cfm)

I've bought nitrotini's at Market Pavilion a few times and they're a neat
novelty.

------
maho
I do not want to discourage people from playing with cool stuff, but for
safety reasons, I would like to give a few examples of what can go wrong:

LN expands by 700x when it evaporates and warms up to room temperature. This
makes thermoses inherently unsafe for storing LN, because _they come with
lids_. Human experience, and the lid itself, through its design, say: Put this
lid on top of the thermos! If you get carried away in the heat of the moment,
you might give into this instinct and accidentally put the lid on the thermos.
Or someone else who was late and missed the safety briefing. Proper lab
equipment, by design, does not come with screw-on tops, for exactly this
reason. If you are hosting an LN cocktail party, I propose that you hide,
throw away, or destroy the lids for the thermoses. A few years ago a German
hobby cook lost his right hand due to putting the lid on his thermos:
[https://translate.google.com/translate?sl=auto&tl=en&js=y&pr...](https://translate.google.com/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.morgenpost.de%2Fbrandenburg%2Farticle1131079%2FKoch-
verliert-eine-Hand-bei-Kuechen-Experiment.html&edit-text=&act=url)

Don't ever swallow liquid nitrogen. Once you ingest it (which actually is
possible) it will rapidly expand by 700x. If you swallow a tablespoong (15ml),
you end up with 10 liters (2 gallons) of gas in your stomach, and it will
rupture. Occasionally you'll see YouTube videos of people doing this, but they
either don't ingest anything, or very small amounts. I would not ever
recommend trying this. Here is an example of the feat going wrong - google "LN
ingestion" for more:
[http://www.ncbi.nlm.nih.gov/pubmed/20065833](http://www.ncbi.nlm.nih.gov/pubmed/20065833)

Don't put things that have been cooled to liquid nitrogen temperature in your
mouth. This is more of a personal story: It was the birthday of one of our
lab-members, and he had brought some warm beer. We naively decided to chill
the bottles with liquid nitrogen. This made most bottles burst and created
huge levels of steam, fun, and what we called "beer popcorn": Beer that had
frozen into small nuggets by the violently boiling liquid nitrogen. Eventually
the birthday-guy decided to try one of the beer nuggets. As he put it on his
tongue, it froze to it. He tried to spit it out, but it froze to his cheek as
well. He did not manage to rip it out in time and had nasty cold-burns in his
mouth. Fortunately, he was not one to easily be bothered by such injuries, so
the party did not end at that moment. But, looking back to it now, the feat
very obviously was a bad idea.

Don't transport large amounts (more than a few liters) of LN in small enclosed
spaces (a car with the windows rolled down, a small basement room). If the
container tips and the gas rapidly boils away, it can dilute the oxygen in the
room to dangerously low levels. Danger starts below 17% or so.

Small splashes of nitrogen won't hurt your hand, but they can hurt your eye.
The cornea of the eye is quite sensitve and (since it has no blood vessels)
heals quite poorly. Most people (not all) recommend safety googles.

LN easily soaks through fabrics - also pretty much all of the fancy
"cryo"-gloves that you can buy in lab equipment stores. While they look like
they might be the right protection for submerging your hands in LN to grab
whatever stuff that fell into the dewar - they won't help.

Touching objects that have been cooled with LN can hurt. If the metals conduct
heat well (metals, for example), they can hurt you more quickly than you would
expect. You can get nasty cold-burns this way. It is good practice to wear
protective gloves (although I sometimes leave them off if bulky gloves makes
handling the ultracold equipment less safe.)

All in all, have fun playing with LN! But I recommend to start with some
simpler experiments(freezing roses and smashing them, ...) first, and then
work your way up to food, and then to alcohol. Be paranoid about pressure
buildups and prevent them by design of the vessels that hold your LN.

~~~
tptacek
We did hide the caps for the thermoses. You didn't read that in my post
because my post is not an instruction manual. I opted instead to keep it
vague, saying instead that sealing LN into a container would kill you.

The point of the thermos is to keep a relatively small amount of LN in your
workspace, so that the bulk of it can be kept out of the house entirely. The
thermos is itself a safety measure.

~~~
2muchcoffeeman
My lab partner back at university once got a very nasty liquid nitrogen burn.
Couldn't use his hand for a few weeks. We even executed emergency procedures
swiftly and correctly.

It was a freak accident, but since then I always cringe when I see articles
like this that have little mention of the dangers involved and appropriate
safety measures.

------
mdholloway
I'm thinking of buying Liquid Intelligence for my sister and brother-in-law,
but I'm half-worried they'll think I'm subtly trying to kill them.

~~~
mattmaroon
I'd recommend it. It's useful if nothing else for the stuff on dilution,
cocktail balancing (acid/abv/sugar percentages), and batching. It's helpful
even for classic cocktails.

Most of the stuff in it is not dangerous. However unless they're nerdy and
willing to spend, they're not going to get much out of the modernist stuff.
I'd say bare minimum you need to build a home carbonation rig (~$150ish) or
buy an ISI Whip and some CO2/N20 cartridges (similar price all-in) and some
Pectinex Ultra-SPL ($15 after shipping) to do anything interesting.

