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Non-freezing shipping
January 22, 2014 7:06 PM   Subscribe

I'd like to ship glass containers carrying liquids to a friend in a Northern state (opening them up and placing them in another container is not an option, as they are carbonated.) It is currently winter and frequently well below freezing outside. Is this possible to do without the contents freezing solid and exploding? FedEx recommends placing thawed gel coolants in a package to prevent freezing as a "heat sink". How does this even work?
posted by Hollywood Upstairs Medical College to Food & Drink (15 answers total) 2 users marked this as a favorite
 
We do this with biological products that are no good if they freeze. The thawed ice packs have a tendency to stay at the same temperature; when the air is colder than they are, they will keep things warmer. I'm not sure why they are termed a "heat sink" in this case as they are acting as the opposite of a sink. Another thing you can do is place everything in a cooler (and then the cooler inside a cardboard box, which I think is required by Fedex). You should also put whatever it is into a ziploc bag with some absorbent material, in case they do break. The absorbent material could be towels, which will also act as an insulator. Finally, you might just want to wait until it's near freezing temperatures rather than -20F; I have definitely delayed shipments, even though I know these precautions help. There are no guarantees, but these things are better than just placing everything in a cardboard box with no insulation.
posted by Tandem Affinity at 7:13 PM on January 22


In general, avoid shipping these items in Polar Vortex conditions. The fact that it is "frequently well below freezing outside" is not the issue. If the outside temperature is +20 degrees Fahrenheit, shipping is no problem. If it is -20, it is.

If you have some flexibility about shipping times, wait until the weather forecasts are in your favor.
posted by yclipse at 7:18 PM on January 22 [1 favorite]


The science-y answer is that water (which is the primary ingredient in an ice pack) has a relatively high specific heat capacity--higher than almost any other common material, and miles better than anything as cheap, safe and common as water. I suspect the other ingredients are there only to provide texture and make punctures less messy.

A "high specific heat capacity" means that the water in the ice packs has to transfer a relatively large amount of thermal energy to the surrounding (colder) environment to drop in temperature by 1° C compared to other materials. This is a fancy way of saying that water cools off more slowly than other tings, and will therefore help to regulate the temperature of what you pack in it.

Technically this is the opposite of what we normally call a heat sink, but the principle is the same. You could think of it as a "cold sink", but cold isn't really a thing--there's only the absence of thermal energy. Of course there are other considerations, like how fast the energy can move out of the water, which is what insulation is for.
posted by pullayup at 7:33 PM on January 22 [1 favorite]


People shipping live reptiles in cold conditions typically use 30+ hour heat packs. I don't know if this would work at all for you, but seems like the same practices might apply here, as both are cargo which absolutely, positively must not be frozen.
posted by Nyx at 8:31 PM on January 22


"In thermodynamics a heat sink is a heat reservoir that can absorb an arbitrary amount of heat without significantly changing temperature."

Heat reservoir.

When they are talking about "heat sink" or "heat reservoir" they are talking about the same principle that this article explains as "Both the ice pack and the non-toxic gel (which is mostly water) can absorb a considerable amount of heat due to the high enthalpy of fusion of water."

In plain English, that means you have to add a lot of heat energy to water to get it to change from ice to liquid. For the same reason, you have to subtract out a lot of heat energy from water to get it to change from liquid to ice.

So, it's a thing that can absorb a relatively lot of heat energy relative to its mass. Thus, a heat sink.
posted by flug at 8:31 PM on January 22 [1 favorite]


Stuff freezes from the outside first, and with time the cold will work its way in. So they are recommending that you surround the outside of the thing you want to ship with a layer of stuff that you don't care if it freezes. However, it is really cold. I suppose you could get lots and lots of cold shielding, which would add to the weight, or as yclipse suggests, wait. Because, Polar Vortex.
posted by otherchaz at 8:38 PM on January 22


You didn't say what you're shipping, but from "glass container" and "carbonated", I'm guessing beer.

I sometimes ship my homebrew beer and cider in the middle of winter.

1) Call your shipping center to find out when their daily pickup is. Plan to arrive an hour early.
2) Wrap each bottle in bubble wrap to prevent breakage. Put the bottles in a styrofoam cooler. Want lots of room in there. Good rule of thumb is a cooler that will hold twice as many plain (no bubble wrap) bottles as you're planning to ship.
3) Pack around the bottles with styrofoam peanuts. Really pack it in there.
4) Lay a sheet of styrofoam or cardboard on top. Activate a chemical heat pack. They usually take about 10 minutes to warm up and stabilize. You can get 30 and 40-hour packs, but I just use the 12-hour hand warmers from the hardware store.
5) Seal the cooler with tape, and put it in a snug-fitting cardboard box. Styrofoam does not hold up well against conveyor belts and rough handling. You don't want a corner getting knocked off and losing your cargo.
6) Ship overnight (1-day service) and you're good.

I've sent beer from Seattle to NY when it was below zero in NY, with no problems. It's crazy expensive, but it works. Last time I sent a dozen bottles, it cost about 90 bucks. Really depends on how badly it needs to get there right now.

(Also remember if it is beer, it's partially alcoholic. Alcohol has a much lower freezing point than water, which is why you can keep vodka in the freezer and it still pours perfectly. That alone won't keep your beer from freezing, but it does help!)
posted by xedrik at 8:42 PM on January 22 [2 favorites]


Could you pack the bottles, wrapped in towels, with a couple of those carbon hand warmer things, all inside cooler? Theoretically, i'm assuming that the hand warmers will emanate heat for about 8 hours, and then the coolers will retain the heat for much longer than that? (The towels provide further insulation, and take up space in the cooler so that there's less air to warm.)
posted by Kololo at 8:57 PM on January 22


You can sometimes get very thick styrofoam coolers for free from places that receive shipments in them, such as pharmacies or veterinary clinics. Put the bottles, wrapped in bubble wrap, and the gel packs inside of that, and put it in an outer box.

How does this even work?

Ever look at an ice cube tray before the cubes have finished freezing? You'll notice that the outer edges have frozen first, leaving the center to freeze last. It works similarly.

If you want to test it out, try freezing two water bottles in your freezer, one with gel packs around it and the other without, and see how long each takes to freeze.
posted by yohko at 9:29 PM on January 22


Carbonated also means the contents are pressurized and take longer/ colder to freeze.
posted by theora55 at 10:56 PM on January 22


Air is your friend. Insulation is your friend.

As others have said above, you need to reverse the principles of keeping something cold in a hot summer.

This means:

- Using an insulated container. A styrofoam box is a cheap option, but check how sturdy it is.
- Bubble wrap. Wrap your bottles in bubble wrap. The air in the bubble wrap will insulate your bottles and keep them warmer longer. [The reverse principle is also true: if you want to cool a bottle of beer rapidly, icy water is better than a deep freeze]. The bubble wrap also, of course, protects your bottles.
- Using gel packs to absorb cold at the bottom of the box, where it will likely be coldest. These packs take a long time to freeze, but stay frozen for a long time when they do. The reverse is true. When warm, they absorb a lot of heat before. Use packing peanuts to separate the gel packs from the bottles as another layer of insulation.

Don't buy gel packs or styrofoam boxes if you don't have to. Doctors and vets have them in abundance because they are used to ship temperature sensitive medicines and toss them regularly
posted by MuffinMan at 2:27 AM on January 23


Know anyone driving, taking a train there, or flying a private plane? Might be an option for these carbonationy containers.
posted by tilde at 3:06 AM on January 23


I don't trust those styro coolers, they fall to pieces way too easily. I like everything in xedricks post except for that.

What i would do, is go to the local big5/REI/joes/etc and check out their returns/scratch and dent area. The bigger stores tend to always have these. I'd also check out my local fred meyers/kroger/walmart/etc for the same. What you want is a slightly beat up, or missing it's fancy internal beer caddy or whatever nice medium-sized proper ice chest. A real, insulated plastic one. The beefiest one you can find that isn't some huge monstrosity with wheels.

Then just build a box around it and ship the thing. Don't bother with packing the cooler in any way. Just tape the thing shut with a couple full wraps then build a box by folding the cardboard exactly the size of the thing.

UPS tends to be the cheapest for shipping large-ish boxes by orders of magnitude. Having a real cooler, i wouldn't bother with 1 or 2 day shipping either. Just throw some of the 40~ hour heat packs mentioned above or even just some of the cheepies in there beforehand and the thermal mass of your bottled stuff+the warmth not really getting to escape should keep you good for a lot longer than you would think, and definitely longer than a styro cooler that might just disintegrate would. You want the heat generating packs AND the gel packs. The hot packs will generate heat for quite a while, and generate meh amounts of heat for a lot longer than their labels say that will not be meh heat in this context. The gel packs will hold on to that for a ridiculous amount of time.
posted by emptythought at 3:10 AM on January 23


I'd throw them in a cooler or other insulated container along with a hot water bottle and lots of insulation/padding. There's a lot of heat in a hot water bottle; if you can keep the contents well-insulated, that heat will stay in the box for a long time.
posted by Scientist at 8:49 AM on January 23


This seems obvious but I'm going to post it anyway: the gel packs should be as warm as possible when you pack them. At least room temperature, and maybe warmed up in a warm water bath if you don't think the heat will damage what you're shipping.

I don't trust those styro coolers, they fall to pieces way too easily.

The kind meant for shipping are almost always sized to fit a matching cardboard box. This prevents any kind of crumbling Styrofoam misadventure.
posted by pullayup at 12:21 PM on January 23


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