Gewgaw cools down coffee to 140 F, then keeps it there for hours

So far 3,383 people have pledged $205,650 on Kickstarter towards the Coffee Joulies project. I didn't know that coffee cooling down too quickly was such a big problem.

Coffee Joulies work with your coffee to achieve two goals. First, they absorb extra thermal energy in your coffee when it's served too hot, cooling it down to a drinkable temperature three times faster than normal. Next, they release that stored energy back into your coffee keeping it in the right temperature range twice as long.

This amazing feat of thermodynamics happens thanks to a special non-toxic material sealed within the polished stainless steel shell. This material is designed to melt at 140 degrees Fahrenheit, and absorbs a lot of energy as it melts. This is how Joulies cool your coffee down three times faster than normal. Once it reaches this temperature, the special material begins to solidify again, releasing the energy it stored when it melted. This is how Joulies keep your coffee warm twice as long.

Coffee Joulies - your coffee, just right

Previously on Boing Boing: Coffee Joulies


  1. So… these are like an anti-ice cube? Except that I have to wash them when I’m done and try not to loose them.

    I think I would rather have the phase change material built into my coffee mug, thermos or thermal carafe.

  2. This hasn’t been on the Boings yet?! Given I’ve heard about it from a half-dozen places, I figured BB would have been my first source.

    They’ve received enough funding that the preproduction AND production units will be made in the US. They were going to send production offshore.

      1. Aha, Chevan, I tried googling with “”, but I didn’t find it. No wonder, glad I’m not entirely losing it.

  3. I live in Michigan. It gets cold there, stays that way for a good chunk of the year. When that happens, coffee doesn’t stay hot for long. It’s a problem.

  4. I also dont understand why building a mug out of the stuff isn’t a better idea. Does it not work as well that way?

    I guess I’m just an easy to please person. I drink my coffee hot, then warm, then I add ice and have an iced coffee. I like it each way.

    1. They’ve addressed the “why not make a mug out of it?” question:

      Two main reasons: 1) Joulies work best in a well insulated container. If the walls of the mug were filled with the PCM instead of doing their normal insulating duties, the mug would be much much less effective at keeping the coffee warm. Plus if it really was working, you would have to hold onto a 140F mug, which wouldn’t be any fun. 2) Surface area to volume ratio. The more “intimate” the mixture of Joulies and Coffee, the faster the mixture will come to equilibrium and the more uniform the temperature will be. If the PCM were in the walls of the mug, we wouldn’t be able to achieve the ability to cool your coffee to the perfect temperature 3x as fast. Even some kind of triple walled mug would be quite a bit less effective in this regard. There are a few more reasons that we made Joulies look the way they do, but these are the two main reasons that guided the design.

    2. I bet it has everything to do with surface area. Several of their “Joulies” have more surface area that’s in contact with the coffee for a longer period of time. So, if you have a vacuum sealed thermal mug (a vacuum makes a great insulator), it stays hot for a long time, but with a Joulie, your coffee would cool down then stay warm even after you’ve finished 2/3rds of your coffee. If it was built into the sides, you’d have a significant amount of the material not in contact with the coffee, and only heating the air surrounding it. If you increased the mug’s surface area, then these nooks and crannies you’ve just created, so that more coffee is in contact with the thermal material, would be a bitch to clean!

  5. Hey, how about drinking normal amounts of coffee at a time, instead of giant gluttonous mugs of the stuff?

    The SCAA standard cup of coffee is 5.33oz.

    Meanwhile, places like Starbucks server coffee in 12oz, 16oz, and 20oz monster sizes! No wonder this guy’s coffee is cold before he can finish it! He’s trying to drink 3 – 4 cups of coffee in a single serving!

    If people are really serious about the quality of their food, they need to look at the amounts they are consuming instead of just the quality of the ingredients and preparation method.

    Besides, all the caffeine is just not good for you.

    (dedicated coffee affectionado)

  6. Spoiler: the proprietary phase change material is going to be a supersaturated solution of sodium acetate. Same material that crystalising hand warmers are made from.

  7. So first of all, a thick mug does much the same thing.

    Second, I figure a cheap knockoff will show up at TJ MAXX in a year or two, and my wife will get one for me as a present.

    Or maybe it will go straight to the late-night infomercial, and then vanish. In that case, it probably wasn’t all that useful.

  8. I’ve never funded a Kickstarter project before. After watching that video, I immediately made an account and invested.

  9. Am I the only one who thinks:

    a) These are exactly the right size and shape to swallow. (Sorry I don’t drink my coffee out of a sippy cup, I’m not two.)

    b) They’re going to knock out my front teeth, just like when you’re tipping back a glass of ice and the ice breaks loose and hits your front teeth? Yeah, except this is stainless steel.

    c) Not microwave or dishwasher safe.

    Make a mug out of it and we’re talking.

    1. I think you’d have to open pretty wide to fit that past your teeth. It looks to be as swallowable as the average ice cube from a large-sized tray.

    2. a) and b): You seem to have an abnormally large mouth and esophagus, as well as really strange ice cubes and a, let’s say, unique way of drinking.

      c): They say it’s dishwasher-safe.

  10. Why not just start a company, have an initial public offering, and let people buy stock?

    I’d be ready to invest $5,000 of my own money in this idea: Provided that’s a purchase of stock which could increase if the project takes off.

    Now, I am just pre-ordering the merch? Not the same….give investors an INVESTMENT in your company, that’s what the stock market is for.

  11. Fourth KS project for me, third to get funded :)

    Anyone know the weight of each bean? Can’t find that anywhere…

  12. 5.3 oz? That’s like a shot. It wouldn’t be worth waiting in line for. Besides, coffee doesn’t have enough caffeine as it is–anyone who really wants to regain consciousness needs one of those Monster beverages with 2 GRAMS of caff!

  13. Add me to the “I don’t even drink coffee but want those”. I wonder if I could convince the chef in our restaurant a box of the 20 set would be good to have, since they’re dishwasher safe

  14. I rarely order coffee b/c I don’t like waiting 15 flippin minutes before it’s cool enough to sip. :-|

  15. Based on similar designs in the building insulation industry, I’m guessing that the secret sauce is probably a type of wax.

  16. “Hours”
    “Twice as long”
    Which one is it?
    Water has a very high heat of fusion and ice doesn’t keep a drink cool for hours.

  17. I doubt I’d use them in my daily “commuter coffee” since my Oxo LiquiSeal Travel Mug does a prety good job of keeping my coffee hot for a fair amount of amount of time. (It’s been 1.5 hours since my current mug was filled, and it’s still quite warm.)

    However, I would be interested to see how they would work in my French Press for those lazy weekends when the amount of coffee brewed is greater than the mug I’m using.

  18. Note: Most of people’s questions (“Why don’t they make a mug out of this?” “Won’t people swallow them?”) were answered last time this was posted.

    Of course, that won’t stop people asking the same questions again.

    I, too, donated after the first time this was posted, my first kick-starter donation. In retrospect, I think I was a little caught up in the cool video — I’m not sure I’d ever really use these regularly in my coffee. But hey, I (assume) I’ll get these once production starts, and we’ll see then.

  19. could we get a string, like a teabag? urge to not touch wet joulies preventing me from becoming more curious.

  20. I fundamentally refuse to support a project that doesn’t use a metric temperature scale, especially when they name their product after an SI unit. I guess that Calorie-ies didn’t have the same ring to it.

  21. i bet you ANYTHING that it’s got sodium acetate (“hot ice”) in it. the melting point is even right.

  22. It seems hilariously chindogu to me, but they seem to have captured the imagination of many and have a successful launch going, so good for them.

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