Stanley Thermos Test (UPDATED)

SEE UPDATES AT END:  Normally I test new gear, however, I’ve had this Red 1.1 Quart Stanley thermos for about 3 years now, (or maybe it’s 4, I forget).  I’ve always loved this thing, it does a great job of keeping coffee hot.  I use it all year long, (I drink a LOT of coffee).   Stanley claims that it will keep hot stuff hot or cold stuff cold for 24 hours.  I have used it many times to make coffee late Saturday morning, pack it up and leave it at base camp and have coffee still good and warm the next morning (Around 20 to 21 hours I estimate).  After a brief discussion with several people who did not think the Stanley could keep coffee hot for 24 hours, we decided to have a “Thermos Showdown”.  (As of the time of this posting, this is the only thermos tested so far).

Sorry for the lousy pic.  The bright blue LED messed it up.  This was the initial setup before I slid it to the cold corner

Sorry for the lousy pic. The bright blue LED messed it up. This was the initial setup before I slid it to the cold corner

The results were actually quite surprising and will require further testing.  There are several factors including whether the thermos was “Primed” (Using hot water to heat the inside elements prior to putting the coffee in it), as well as the outside temperature. (This was tested at approximately 63 degrees air temp).  (Colder area near the floor at an outside wall of the house.  This was verified by the 3rd and 4th sensors on the digital temperature gauge.

Note on Priming.  I did not prime my thermos the first 2 or 3 times I used it, but a scouting friend pointed it out to me at that first summer camp with it and I’ve primed it ever since.  I do not know how much of a difference it makes, but will find out in future tests.

The following results included these conditions:  63 Degree air temp and Percolated coffee at 212 degrees and a thermos that was primed with 212 degree water for 10 minutes.

The bottle was sealed for the first 10 hours but I thought there had to be something wrong with the sensor that it only lost 9 degrees in 10 hours, so I opened it and dropped in a second sensor.  There was a dramatic temperature loss after opening it of 6 to 9 degrees an hour.  So I’m going to want to re-run the test without opening it. (There was nothing wrong with the sensors by the way.  Both read identically to the tenth of a degree).

I had to leave for work the next morning so my last read was at 5:45 AM (Written down as 6:00 on the chart)  at 154 degrees which is still plenty hot for drinking).  At the 24 hour mark I buzzed my son to get a final 24 hour temp and was surprised when he told me it was still 149.   I didn’t give it another thought.  Got home to get ready for a Cub Scout meeting and decided to pull the thermos and dump it, figuring it would be too cold to drink.  But in that last 6 hours it only lost 6 more degree!!.   The final temp before I opened it was 143 degrees after 30.5 hours and it was still respectably warm to drink.  Not lip burning hot by any means but more than warm enough to drink. (And the coffee still tasted pretty darn good too, LOVE my Palermo Coffee) I was totally blown away it was still that warm.  I truly expected it to be at room temp after 30.5 hours.

The Chart shows the measured temps (Estimated between 2:00 AM and 5 AM by the 10 degree drop)

The Chart shows the measured temps (Estimated between 2:00 AM and 5 AM by the 10 degree drop)

I’m going to re-run the test with a few other conditions.  Such as not priming it first, as well as putting it outside the front door while the outside temps are below 10 degrees and also test it without opening the entire time (Which is how I normally use it) as well as opening it and pouring a cup out every couple hours.   Expect those tests in follow ups in the future.

All in all, I am pleasantly surprised by these results.  And the Stanley’s claim of 24 hours is on the mark.   Now I need to borrow the thermos models my friends have and put them all in a back to back test.  (I can do 4 at a time with 4 sensors).  It will be interesting to see how they all compare.

UPDATES: Stanley un-primed and Walmart Thermos Primed.

Since the first test, I have had a chance to rerun the test on the Stanley without priming it, as well as run the 2.1 Quart Walmart Brand Thermos in another back to back test.  First things first.  The difference between priming and not priming is SUBSTANTIAL in the first 8 hours.  Checking out the side by side results below, you can see that not only did we lose 10 degrees in the first 10 minutes to the prime, the temp drop reached nearly 24 degrees cooler in the first 8 hours. After that the temps leveled off and by 24 hours were roughly 4 degrees different. So for long term (24 hour) storage, priming doesn’t make as significant a difference, but in the at first 6 to 8 hours (Typical for Lunchtime or normal workday use), priming makes a good bit of difference.

Thermos Brand 40 oz and Stanley Red 1.1 Quart

Thermos Brand 40 oz and Stanley Red 1.1 Quart

Now on to the Thermos model 2.1 liter compared to the Stanley.  The Stanley came out of the gate better, holding temp roughly half way between the primed and un-primed tests of the Stanley.   At the 8 hour mark, it was holding 5 degrees hotter than the un-primed Stanley, but 19 degrees behind the primed Stanley.  And after 24 hours, all three thermos tests were within a few degrees of each other at roughly 145 which is plenty warm for drinking/eating.

All in all, either thermos will work, but the Stanley 1.1 quart does perform better when primed than the Thermos brand.

Thermos Test

Side By Side, Stanley Primed, Un-primed and Thermos brand.





About Docwatmo

Just an average guy reviewing equipment for the average guy (or gal). View all posts by Docwatmo

6 responses to “Stanley Thermos Test (UPDATED)

  • Raval Dev

    What is the maximum temperature stanley can withstand and start melting ?
    Which can melt first thermos, Stanley or the unprimed?
    Can i use it for 300-400 Degrees Celcius as a storage?
    Answer me as soon as possible.
    Thank you

    • Docwatmo

      Considering the bulk of the liquid contact surface is stainless steel those temps would be possible, however since the bottom of the lids are made from polypropylene injection molded plastics with a rubber seal, the lowest common denominator would say that since this plastic melts at roughly 338 degrees Fahrenheit (170 Celsius), that the temps you are talking about are far higher than what these bottles can take and would rapidly melt the lids.

  • Brian Beatty

    You’re testing seems impressive enough. You should try it with real world usage. By that I mean open and close long enough to fill the cup up with coffee. I’m guessing once an hour if out in the woods. Or once or twice every 2 to 4 hours resembling a coffee break and then lunch break. Because you are going to lose temperature opening the bottle to pour your cup which everybody does.

    • Docwatmo

      Great Idea, I had considered doing that. But the overall thermal dynamics of the canisters would follow the same rates of decay as the other tests. (Yes, it would affect the length of time the liquids stay cool). I just might do a follow up post some time doing that. Thanks for the input!

  • John Kruse

    My Father had the “1951- Stanley”
    with Cork Stopper at the
    Cement Plant. Later on, It had
    Twin Wrap Around Springs With a
    Single Plastic Handle. It was in use
    till it was lost to One in the
    Family, 1999.

    • Docwatmo

      My grandfather had one of the old Stanley’s like that, and he also had one that had the glass vacuum bottle inside. Really ancient. Love the Stanley’s. Tough as nails.

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