The temperature equalizing sounds interesting. I'd try Joeveo out if one happened to be offered by a friend or something, but it'd have to be pretty special to displace my Thermos travel mug. I've been using the same one for 15 years and it still keeps my drink warm for hours.

Lid is tight and leak proof. I trust it inside my pack. The handle and carabiner are essential components too. Handle hangs over bike handlebars, side of canoe or seat, belt. Carabiner does, well it does what carabiners do!

https://imgur.com/a/5f9rMA2 This pic is from 2014. It's lost the rubber base since then but none of its usefulness.

Ah, shucks. They don't ship to Europe :(

"Please note: because of recently-instituted tax collection requirements, we are no longer shipping to the EU or UK—sorry!"

There must be something available in Europe, I remember then-chancellor Rishi Sunak getting some stick for having a £200 heated mug with Bluetooth. Of course, now he's running the place.

There are services in US which will gladly give you an address in US and forward to almost all countries in the world. Search for "us package forwarding"

Oh neat, I didn't know that. Thank you.

Looks like a run of the mill aluminum air insulated mug. What’s special about this brand?

In addition to the normal vaccuum insulation layer, it has a layer that does a (constant-temperature) phase change at ~140F. If your drink is hotter than this, energy flows out of the drink, cooling it and liquifying the layer. If you drink is cooler, energy flows into the drink, solidifying the layer.

grep for technogeek [here](https://joeveo.com/pages/the-temperfect-mug)

Just a quick, non-hostile technical nitpick: I don't believe that at any point, energy will actually be flowing back into the drink. If the drink is cooler, the insulator layer will become a significantly worse conductor, preventing heat from flowing outward as well as from the liquid-phase insulator, but thermodynamics/the law of entropy shouldn't really allow for the energy to flow back into the liquid, even when the insulator does re-solidify.

If you open the mug and rapidly cool the drink (eg dropping a few ice cubes in), heat should be flowing back into the drink?

(I mean that's not a crazy notion: if you have any warm mug and fill it with cold stuff, the warm mug will heat up your cold stuff.)

You are right that if you keep your mug closed, there shouldn't be any energy flowing back into your drink.

If you rapidly cool the drink, you're definitely right - energy would flow PCM -> drink. Otherwise, it's semantic if GP is correct. There would be dynamic equilibrium, i.e. flow of thermal energy in both directions, but no true flow from PCM->drink.

The steps would be:

1) Drink > 140, PCM solid

2) energy flows drink -> PCM, drink cools toward 140, PCM liquifies gradually

Then two possibilities:

3a) drink cools to 140-epsilon before PCM liquifies fully

4a) PCM gives energy to drink in dynamic equilibrium, while also losing energy to environment, solidifying

5a) PCM is entirely solid at 140

6a) PCM drops below 140. drink gives energy to PCM and PCM to environment. drink -> PCM thermal conductivity is presumably much higher than PCM -> env, so drink and PCM remain at same temp

OR

3b) PCM liquifies fully before drink hits 140-epsilon

4b) drink and PCM stay at thermal equilibrium (see 6a) while cooling toward 140. energy flows drink -> PCM and PCM -> environment. The former is faster, so the PCM continues liquifying

5b) PCM is entirely liquid at 140. Due to thermal equilibrium, drink is also at 140.

6b) drink stays at 140 while PCM solidifies

7b) see 5a

8b) see 6a

You seem to assume that the PCM encapsulates the drink on all sides. But the cup has a lid, which doesn't have a PCM inside, and which isn't perfectly isolated.

So there will be energy going from the drink to the environment through the lid, which in turn allows energy to flow back from PCM -> drink.

When the "insulator layer" (a phase change material or PCM) is between phases, it can absorb or emit energy without changing temperature.

The drink on the other hand will change temperature as it looses energy.

The drink will lose energy through the lid, leading to a small temperature gradient between the PCM and the drink. This gradient should allow energy to flow back from the PCM into the drink.

Its „Temperfect insulation“ is most likely a PCM i.e. a phase changing material storing heat in a phase transition. It absorbs or releases heat depending on the outer temperature by means of a physical phase transition (not sure if this is really liquid-solid but perhaps a crystal reconfiguration).

Sigh, anywhere I can buy this for my wife and I in Australia? The shipping for 2 cups is $60 USD, and it all totals out to something like $250 AUD which is completely unjustifiable.

Insulated keep cup on display at any cafe is around $15-25 AUD.

That's not likely to get you a winning mug, if threads complaining any the fake reviews and fake products off Amazon. Better to buy direct if you want a mug that's actually made out of thick enough aluminum to resist breaking, and actually has a vacuum to insulate. Otherwise you'll get one insulated by dirty diapers.

https://www.yeti.com/ would be my preferred vendor for that sort of thing.

I didn't know yeti used old diapers for insulation, but thanks for raising awareness!

Project Farm did a video comparing insulated water bottles and Yeti didn't perform so hot

https://www.youtube.com/watch?v=a6j1NJkNzwI

Pelican cups have a "sippy lip" on them which is really nice for drinking, feels like a normal cup. It looks like Yeti has partially recessed their lid now, not sure if it's deep enough from the picture. https://www.pelican.com/us/en/products/drinkware

Website says there's a layer of insulation between the vacuum walls.

I literally hadn't heard of this brand until this comment, but I figured it was worth pointing out that their "layer of insulation" is a bit more complex than it might seem at surface level, being a phase-change insulator.

They claim that it changes phase right around the 63 degC mark (which, again, is claimed to be the sweet spot for where most hot beverages are enjoyed). Therefore, a hot drink will quickly move to that temperature when the poured liquid is above that transition temp (the liquid-phase insulator being a good conductor), and then stay close to it after dropping below the transition point, when the solid insulator re-forms and stops conducting heat well. If true, I think it's a really neat application of high-tech materials science in everyday life.

[1] https://joeveo.com/pages/the-temperfect-mug (see "Details for the Technogeek)

Thanks for letting us know, that sounds really cool, I just bought one myself!