Any small but good thermos flasks?

[BobM]

I am looking for a good thermos flask to keep about 500ml (1 pint to our American friends) of coffee piping hot for 5 or 6 hours, say, when I want to take a coffee break on the road ( I know the best flask at such times is actually a café, but please bear with me for a moment).

When I asked for a thermos flask in an equipment shop the staff did not know what a thermos flask was and showed me cheap containers with insulation between the double walls that masqueraded as real vacuum flasks.

So, if anyone can point me to a good thermos flask I would sing your praises to the heavens - and drink a toast to you every time I used it.

Bob M

 

[Nana6]

I am looking for a good thermos flask to keep about 500ml (1 pint to our American friends) of coffee piping hot for 5 or 6 hours, say, when I want to take a coffee break on the road ( I know the best flask at such times is actually a café, but please bear with me for a moment).

When I asked for a thermos flask in an equipment shop the staff did not know what a thermos flask was and showed me cheap containers with insulation between the double walls that masqueraded as real vacuum flasks.

So, if anyone can point me to a good thermos flask I would sing your praises to the heavens - and drink a toast to you every time I used it.

Bob M

Amazon has a Thermos 16 oz Stainless steel commuter bottle that stays hot for 8 hours if in US
Most others will just be the plastic insulated

 

[VNwalking]

Sigg makes a brilliant one.
It's not cheap, 25 Euros, but a vaccum flask that keeps things hot or cold for ages. I got mine on a whim at the Zurich airport and since then it's gone with me everywhere.

US Home page

sigg.com

 

[BobM]

Amazon has a Thermos 16 oz Stainless steel commuter bottle that stays hot for 8 hours . . .

Well done, Nana6. Amazon Australia sell a similar product for $36 that I will check out.

Bob M

 

[Dean West]

Yeti brand is supposed to be amazing keeping things hot or cold

 

[VNwalking]

I don't know about Yeti - but I can say from experience that the Sigg keeps things hot for 10+ hours, and cold for longer. (It says it will keep hot for 12, but I never leave things that long.)

 

[Jeff Crawley]

I heartily recommend the Zojirushi from Japan. If you "temper" the flask by filling it with boiling water first (some cafes will do this for you) the drink will stay amazingly hot for 8 - 10 hours. The problem is that you'll most likely burn your tongue sipping it in the first 3 - 4 hours.
I have a 330ml one which weighs 566g full/261g empty and a 400ml one which is 681/290g. There's also a 600ml one which I'm guessing would be a whopping 900g+ full?
There is a "sippy lip" to drink from and a safety lock on the cap prevents it popping open - one test I read before buying included putting a full flask, wrapped up in a towel, inside a tumble dryer - the Zojirushi passed with no leaks.
You can find them on eBay Australia too but they come from Japan so you'll get hit by a 10% GST.

 

[gschmidl]

I can second the Zojirushi. Jeff seems to have mis-linked so here you go.

 

[rorerich]

Yeti brand is supposed to be amazing keeping things hot or cold

Yeti has a good reputation - and yes, it is a true vacuum bottle. There are more than several choices, but this is what I believe you might be looking for:

YETI 12 oz Insulated Kids Water Bottle

Our popular 12 oz kids bottle is dishwasher safe, made of kitchen-grade stainless steel and comes in many colors. Insulated, reusable, 100% leakproof. Shop now.

www.yeti.com

 

[RuediG]

Are there any good light-weight ones? Sigg looks good, but hauling an extra 310gr / 11 oz.. day in day out just for the pleasure of a morning cup of coffee seems excessive.

 

[Jeff Crawley]

I can second the Zojirushi. Jeff seems to have mis-linked so here you go.

Well spotted, now fixed. Yours is a different flask to mine but no doubt just as good.

 

[Jeff Crawley]

Are there any good light-weight ones? Sigg looks good, but hauling an extra 310gr / 11 oz.. day in day out just for the pleasure of a morning cup of coffee seems excessive.

It's like the old engineering triad of cheap/light/strong - pick any two i.e. you can have cheap and light but it won't be strong.
As far as I can see if you get a flask that keeps things hot it won't be light. If you get a flask that's light it won't keep the contents hot for an extended period.
Nobody could ever accuse a caffeine addict of lack of excess!

 

[MikeyC]

We also think highly of Zojirushi and find the Tiger brand (also Japanese ) just as good.
Their food containers are also great and can be used to prepare rice. Put rice in, add boiling water, screw tight and it cooks in a few hours.
(Robo, this might replace the rice cooker!)

 

[Jeff Crawley]

We also think highly of Zojirushi and find the Tiger brand (also Japanese ) just as good.
Their food containers are also great and can be used to prepare rice. Put rice in, add boiling water, screw tight and it cooks in a few hours.
(Robo, this might replace the rice cooker!)

Replace the rice cooker? What heresy is this?

 

[Davidmm]

Stanley, comes with a lifetime warranty.

 

[Jacobus]

I am looking for a good thermos flask to keep about 500ml (1 pint to our American friends) of coffee piping hot for 5 or 6 hours, say, when I want to take a coffee break on the road ( I know the best flask at such times is actually a café, but please bear with me for a moment).

When I asked for a thermos flask in an equipment shop the staff did not know what a thermos flask was and showed me cheap containers with insulation between the double walls that masqueraded as real vacuum flasks.

So, if anyone can point me to a good thermos flask I would sing your praises to the heavens - and drink a toast to you every time I used it.

Bob M

Anything made by Yeti keeps drinks cold or hot up to and beyond 24 hrs. Expensive but worth it. Try Bass Pro or Cabellas
Cheers Jim

 

[debra]

This is a great thread but does anyone have a link to a study by a site like backing packing lite or backcountry gear that reviewed a set of them for which worked best?

 

[BobM]

Thanks to everyone for such excellent suggestions.

I just bought the Thermos Flask shown in the weblink from Amazon for $A36. I have not used it yet, but it is a little heavier (400gm empty) than I expected, but Jeff Crawley's triad is probably working as nature decreed.

The flask holds 470ml (roughly 2 standard cups I think) - a little more than I want for a flask to carry on a walk. I think the Zojirushi 3330ml flask that Jeff mentioned would be a better choice for hikers who want to travel light and compact. I would suggest checking this brand out before buying a Thermos brand.

Sigg (genuine - not the cheap lookalikes) also make good products. I have used Sigg water bottles for years. They are dented and scraped, but the seals work perfectly. They also make good hot water bottles if you have to boil drinking water. I assume Sigg flasks are equally solid and reliable.

Of more concern is the drinking top, which relies on two little plastic bumps to seal the drink opening and pressure equalisation hole that you can see in the photo. As a hot drink cools a slight vacuum would develop in the flask and make a tighter seal, but the reverse would be the case for cool drinks.

Over time those little knobs may fail and potentially ruin a good flask. But you can detach the flexible white piece of rubbery plastic with the bumps on it and probably buy a replacement as indicated on the Thermos Flask website. I have not checked that out, but if it is possible I would suggest buying a spare.

I have seen variants of this sealing method on other flasks, so maybe it is standard for convenient 'sippable' flasks that don't require a separate cup. It would be great if folks could comment or post pics of the sealing arrangement on their flask.

Apart from that, the flask is well-designed and made. The lid has a safety 'ring' over the release button to prevent it flipping open accidentally in a pack. The lid is also spring-loaded, so it stays away from your face when you take a sip without having to hold the lid out of the way.

Hope this is helpful.

Bob M

 

[BobM]

. . . does anyone have a link to a study by a site like backing packing lite or backcountry gear that reviewed a set of them for which worked best?

The UK consumer magazine Which? has a review of reusable coffee cups and travel mugs but they are not real flasks. Nevertheless the website might give some useful tips about what to look for.

Another review gives a few tips, but does not focus on compact flasks for hikers.

Bob M

 

[VNwalking]

I assume Sigg flasks are equally solid and reliable.

As I said above. Yes. Very much so. I love the one I have.
It holds the heat much longer than the other brands I've tried (I haven't used the thermos, though so can't say about that one).
And yes...it's beginning to collect dents, like all good Sigg flasks. But that doesn't affect its performance.

 

[BobM]

I have a bit of time on my hands, so here is a bit of pedantic trivia about why flasks keep cold drinks colder❄ for longer than hot drinks hot (excuse tortured English).

A hot drink may be 80 degrees C or more when it is first poured into the flask. If the ambient temperature is 25 degrees C, the temperature difference is at least 55 degrees.

A cold drink will never be colder than 0 degrees C, so on a 25-degree day the temperature difference will be only 25 degrees max.

So, hot drink delta T is 55 degrees, cold drink delta T is 25 degrees. Any questions?

Bob M

 

[VNwalking]

Any questions?

I'll bite.
What if you preheat or pre-cool the flask? That doesn't change the ambient deltaT, but it adds a bit of time to how long things stay hot or cold, yes?

 

[BobM]

What if you preheat or pre-cool the flask? That doesn't change the ambient deltaT, but it adds a bit of time to how long things stay hot or cold, yes?

An excellent point. I like the way you question assertions. A very valuable trait.

Preheating/cooling the flask will reduce the immediate heat loss/gain caused if the drink itself had to heat/cool the flask and lose/gain temperature as a result, so it definitely gives you an advantage.

You can calculate the advantage knowing the thermal properties of the flask and engineering students studying heat transfer learn how to do such calculations. It fills in the time.

Bob M

 

[VNwalking]

engineering students studying heat transfer learn how to do such calculations. It fills in the time.

That's not me. But good to know the advantage. I'll keep pre-heating my Sigg.

 

[debra]

This is a great thread but does anyone have a link to a study by a site like backing packing lite or backcountry gear that reviewed a set of them for which worked best?

OK a link of reviews by backpacking sites as most of us have a only had a few of the current for sale thermoses.

We Tested a Bunch of Insulated Thermoses to Guarantee Steaming Hot Coffee and Ice-Cold Water

We tried out thermoses from brands like Stanley, Yeti, and Otterbox to find the best insulated containers for your lunch.

www.popularmechanics.com

12 Best Hiking and Camping Thermoses | KeepitHot

One of the main essentials that must never be forgotten while packing for your hiking or camping trip is definitely a reliable thermos flask! A thermos will keep your food and drinks at the desired temperature throughout your trip regardless of the weather conditions. How to pick the best hiking...

keepithot.co

The 9 Best Thermoses & Insulated Bottles [2023 Update] - My Open Country

Looking for the best thermos for your hiking and camping adventures? Our guide has you covered!

myopencountry.com

thermos - Backpacking Light

anyone use a nalgene with insulation for thermos, my thermos lid is leaking and waiting to hear back from snow peak if they have replacement lids for there kanpai thermos,...

backpackinglight.com

10 Best Thermoses for Hunting in 2021 - Outdoor Gear Up

A thermos is the perfect addition to your next hunting trip. Make sure you pick the right one by checking out the top ten best thermoses for hunting!

www.outdoorgearup.com

Please note those are only the first I found with a backpacking thermos reviews

 

[Jeff Crawley]

An excellent point. I like the way you question assertions. A very valuable trait.

Preheating/cooling the flask will reduce the immediate heat loss/gain caused if the drink itself had to heat/cool the flask and lose/gain temperature as a result, so it definitely gives you an advantage.

You can calculate the advantage knowing the thermal properties of the flask and engineering students studying heat transfer learn how to do such calculations. It fills in the time.

Bob M

You need to take into account the specific gravity (density) of the materials involved (flask, liquid etc.) as well as their masses and relative temperatures: calorimetry, one of the few parts of thermodynamics I can still recall!

 

[dougfitz]

OK a link of reviews by backpacking sites as most of us have a only had a few of the current for sale thermoses.

We Tested a Bunch of Insulated Thermoses to Guarantee Steaming Hot Coffee and Ice-Cold Water

We tried out thermoses from brands like Stanley, Yeti, and Otterbox to find the best insulated containers for your lunch.

www.popularmechanics.com

12 Best Hiking and Camping Thermoses | KeepitHot

One of the main essentials that must never be forgotten while packing for your hiking or camping trip is definitely a reliable thermos flask! A thermos will keep your food and drinks at the desired temperature throughout your trip regardless of the weather conditions. How to pick the best hiking...

keepithot.co

The 9 Best Thermoses & Insulated Bottles [2023 Update] - My Open Country

Looking for the best thermos for your hiking and camping adventures? Our guide has you covered!

myopencountry.com

thermos - Backpacking Light

anyone use a nalgene with insulation for thermos, my thermos lid is leaking and waiting to hear back from snow peak if they have replacement lids for there kanpai thermos,...

backpackinglight.com

10 Best Thermoses for Hunting in 2021 - Outdoor Gear Up

A thermos is the perfect addition to your next hunting trip. Make sure you pick the right one by checking out the top ten best thermoses for hunting!

www.outdoorgearup.com

Please note those are only the first I found with a backpacking thermos reviews

These links are great, but don't appear to have confirmed the manufacturers performance claims with other testing.

I have tested a variety of vacuum flasks that I have collected over the years. Salewa, Stanley and Kathmandu all produce 500 ml flasks that have good heat retention properties. The standout performer in my current collection is from Kathmandu. This is a flask that I bought heavily discounted on sale. The flask is the lightest of the three, and heat retention is only a little less than the Salewa.

Note that older Kathmandu flasks of this size did not perform as well as the Salewa, and I might have been just lucky getting one that was a good performer.

Also note that these smaller flasks don't keep water hot enough to brew tea for more than a couple of hours, but are still fine for making coffee after three or four hours.

 

[debra]

These links are great, but don't appear to have confirmed the manufacturers performance claims with other testing.

I have tested a variety of vacuum flasks that I have collected over the years. Salewa, Stanley and Kathmandu all produce 500 ml flasks that have good heat retention properties. The standout performer in my current collection is from Kathmandu. This is a flask that I bought heavily discounted on sale. The flask is the lightest of the three, and heat retention is only a little less than the Salewa.

Note that older Kathmandu flasks of this size did not perform as well as the Salewa, and I might have been just lucky getting one that was a good performer.

Also note that these smaller flasks don't keep water hot enough to brew tea for more than a couple of hours, but are still fine for making coffee after three or four hours.

I am glad that you like them I was hoping one of them was more a a group test of the flacks but I only posted the first five google hit. I didn't read them but would love to know if there is a study of say 5-10 of the top flacks of the temp taken once an hours for ten hours.

 

[henrythedog]

Big flasks always work better than small flasks, everything else being equal - surface area to volume ratio.

Having said that, I use a Lifeventure 300ml flask and rate it very highly. I always ‘prime’ it before filling it, only ever fill it with water, and always stuff it inside my spare sock (singular - it’s a pilgrimage not a fashion show) in the middle of my pack. Whether the extra insulation makes a difference or not, I don’t know - but why not?

 

[dougfitz]

I am glad that you like them I was hoping one of them was more a a group test of the flacks but I only posted the first five google hit. I didn't read them but would love to know if there is a study of say 5-10 of the top flacks of the temp taken once an hours for ten hours.

Here are the results of a test I ran today on four small flasks:

Time	Lifeventure 350ml	Stanley 500ml	Kathmandu 500ml	Salewa 500ml
Pre Heat Temp (C)	95	95	96	96
10 min	96	97	97	98
1 hour	89	94	93	93
4 hours	75	85	84	85
Weight Full, gm	619	919	802	886
Weight Empty	292	449	328	405
Effective Capacity	327	470	474	481

I live at an elevation of about 550 m ASL, so water boils at a little under 100 deg C. The ambient- temperature at the time of fill was 20 deg C, and each flask was pre-heated for five minutes before being refilled with freshly boiled water. The test procedure might have slightly favoured the Lifeventure and Stanley flasks over the Kathmandu and Salewa, but for these purposes, I doubt there was much in it.

Edited following a second capacity measurement.

 

[VNwalking]

Mine is the Sigg Thermo Flask 500ml
Weight empty is 315 gm
Weight full is 315 + 500gm = 815gm (a half litre of water is by definition 500gms)
Effective capacity is a bit over 550ml
The Sigg specifications claim, "This thermo flask keeps your drink 12 hours hot and 18 hours cold."

I'll try @dougfitz 's temperature tests and check back with results.
It's a pity that all those reviews do not include this one; it's the best I've tried. In terms of weight they're lighter than the ones Doug has tested, and I can say with confidence (and burned lips) that they keep things really hot for a long time. (Sigg is Swiss, and the reviews are American, which may explain a few things. I'm not Swiss but find that my annoying Swiss friends are usually right when they say Swiss people make things better. )

 

[debra]

Here are the results of a test I ran today on four small flasks:

Time	Lifeventure 350ml	Stanley 500ml	Kathmandu 500ml	Salewa 500m
Pre Heat Temp (C)	95	95	96	96
10 min	96	97	97	98
1 hour	89	94	93	93
4 hours	75	85	84	85
Weight Full, gm	619	919	802	886
Weight Empty	292	449	328	405
Effective Capacity	327	470	474	481

I live at an elevation of about 550 m ASL, so water boils at a little under 100 deg C. The ambient- temperature at the time of fill was 20 deg C, and each flask was pre-heated for five minutes before being refilled with freshly boiled water. The test procedure might have slightly favoured the Lifeventure and Stanley flasks over the Kathmandu and Salewa, but for these purposes, I doubt there was much in it.

Edited following a second capacity measurement.

Thank you
I find that to very helpful.

 

[henrythedog]

Doug

That’s excellent.

Do you think that ‘big is better’ explains a good proportion of the difference in performance?

The lifeventure flask performs least well, but is quite considerably the smallest in volume.

David

 

[dougfitz]

Doug

That’s excellent.

Do you think that ‘big is better’ explains a good proportion of the difference in performance?

The lifeventure flask performs least well, but is quite considerably the smallest in volume.

David

I would be speculating. There are differences in design between the four flasks. For example, the Salewa and Kathmandu flasks are essentially the same height, but the Kathmandu flask diameter its slightly larger, hence has a slightly larger total volume. Given that the Kathmandu flask has slightly less effective volume, it implies that the internal diameter of the flask will be slightly less. Further, given that the Kathmandu flask is also lighter, any volume differences cannot be explained by material thickness, but can be explained by the Kathmandu having a larger vacuum space, ie by having a greater separation between the inner and outer walls of the flask. This would clearly influence the performance of the flask. The Salewa design or manufacturing process might create advantages that I cannot detect that balance that out.

The other difference is the seal cap and outer cap/cup. The Stanley and Lifeventure flasks have a simple one piece seal cap with a pour slot below the neoprene seal. The others have an arrangement where a plastic plate is unsealed by pressing a button on the top of the cap. The relatively thin plastic plate would not appear to offer a high level of insulation, but nonetheless seems to work reasonably well.

If I can find the time, I might see if I can find a selection of one litre flasks to test whether they perform better than the 500 ml flasks. If they did, I would feel more comfortable suggesting larger is better is a reasonable statement to make.

 

[dougfitz]

If I can find the time, I might see if I can find a selection of one litre flasks to test whether they perform better than the 500 ml flasks. If they did, I would feel more comfortable suggesting larger is better is a reasonable statement to make.

Here are the results of today's testing activity:

Time	Alladin 0.95 li	Thermos ~ 1 litre (capacity not stated)	No name hot/cold flask ~500 ml
Preheat (deg C)	95	96	95
10 min	99	99	97
1 hour	96	96	93
4 hours	91	89	80
Weight Full (gm)	2104	1694	755
Empty	1188	728	295
Effective capacity	916	966	460

Ambient temp at start: 20 degC.

This gives some support to the bigger is better line, but clearly that isn't going to explain all the differences in measured performance.

 

[Margaret Butterworth]

I have a small Thermos flask which is about 40 years old and still going strong. It only holds 250 ml inside, ideal for coffee for one on a bushwalk in Australia. I would not take it on any Camino, because it's all extra weight and I prefer to stop at a cafe. The interior of the flask is glass. It seems impossible to buy this type any longer.

 

[Jeff Crawley]

Here are the results of a test I ran today on four small flasks:

Time	Lifeventure 350ml	Stanley 500ml	Kathmandu 500ml	Salewa 500m
Pre Heat Temp (C)	95	95	96	96
10 min	96	97	97	98
1 hour	89	94	93	93
4 hours	75	85	84	85
Weight Full, gm	619	919	802	886
Weight Empty	292	449	328	405
Effective Capacity	327	470	474	481

I live at an elevation of about 550 m ASL, so water boils at a little under 100 deg C. The ambient- temperature at the time of fill was 20 deg C, and each flask was pre-heated for five minutes before being refilled with freshly boiled water. The test procedure might have slightly favoured the Lifeventure and Stanley flasks over the Kathmandu and Salewa, but for these purposes, I doubt there was much in it.

Edited following a second capacity measurement.

Impressive research Doug. I was going to do something similar with my Zoji's - just need to find the thermometer!

Reminds me of a Victorian explorer I once read about. He traveled the world with a copper kettle fitted with a thermometer brewing tea at different altitudes. English of course.

Tomorrow morning is taken up with a hospital appointment but might have some data to add to your spreadsheet tomorrow evening.

 

[Jeff Crawley]

Here are the results of a test I ran today on four small flasks:

Time	Lifeventure 350ml	Stanley 500ml	Kathmandu 500ml	Salewa 500ml
Pre Heat Temp (C)	95	95	96	96
10 min	96	97	97	98
1 hour	89	94	93	93
4 hours	75	85	84	85
Weight Full, gm	619	919	802	886
Weight Empty	292	449	328	405
Effective Capacity	327	470	474	481

I live at an elevation of about 550 m ASL, so water boils at a little under 100 deg C. The ambient- temperature at the time of fill was 20 deg C, and each flask was pre-heated for five minutes before being refilled with freshly boiled water. The test procedure might have slightly favoured the Lifeventure and Stanley flasks over the Kathmandu and Salewa, but for these purposes, I doubt there was much in it.

Edited following a second capacity measurement.

So in the end I did the experiment this evening:

Time	Lifeventure 350ml	Stanley 500ml	Kathmandu 500ml	Salewa 500ml	Zojirushi 400ml	Zojirushi 400ml
Pre Heat Temp (C)	95	95	96	96	23.7	96.4
10 min	96	97	97	98	94.1	96.7
1 hour	89	94	93	93	87.8	89.7
4 hours	75	85	84	85	71.2	72.1
Weight Full, gm	619	919	802	886	668	664
Weight Empty	292	449	328	405	296	290
Effective Capacity	327	470	474	481	375	375

My 400ml Zojis fall between your Lifeadventure and Stanley in size. I ran the two flasks side by side but tempered one with boiling water first and left the other at ambient temperature (23.7C). The results seem to indicate what you'd expect - larger flasks retain heat better due to the greater mass of their contents.

What surprised me was that, like yours, the temperature rose slightly in the pre-heated flask after 10 minutes but that, after 4 hours there was little difference in the temperature of my pre-heated and ambient flasks. I've always thought that pre-heating or tempering improved heat retention but apparently not by that much. Perhaps on a colder day?

The supposed idea temperature for brewing coffee is 85C so 70+ after 4 hours isn't too bad. One thing I learned is not to stick your finger into 71C water to see how hot it is (160F for all who speak "old" units) - the answer is "hot enough".

 

[cameronon]

I recommend yeti and hydro flask. I have both brands of thermos flasks, and I like them too. Although their prices are a bit expensive, they are worth the money. You can decide which one you need in the comparative article: https://www.gearhunder.com/yeti-vs-hydro-flask/

 

[trecile]

I recommend yeti and hydro flask. I have both brands of thermos flasks, and I like them too. Although their prices are a bit expensive, they are worth the money. You can decide which one you need in the comparative article: https://www.gearhunder.com/yeti-vs-hydro-flask/

They are awfully heavy aren't they?

 

[Jeff Crawley]

But imagine how impressed your fellow Pilgrims will be when you tell them you're hauling a half gallon of coffee . . .

 

[Davidmm]

I recommend yeti and hydro flask. I have both brands of thermos flasks, and I like them too. Although their prices are a bit expensive, they are worth the money. You can decide which one you need in the comparative article: https://www.gearhunder.com/yeti-vs-hydro-flask/

We use Stanley flasks. They come with a lifetime replacement warranty

 

[Davidmm]

I am looking for a good thermos flask to keep about 500ml (1 pint to our American friends) of coffee piping hot for 5 or 6 hours, say, when I want to take a coffee break on the road ( I know the best flask at such times is actually a café, but please bear with me for a moment).

When I asked for a thermos flask in an equipment shop the staff did not know what a thermos flask was and showed me cheap containers with insulation between the double walls that masqueraded as real vacuum flasks.

So, if anyone can point me to a good thermos flask I would sing your praises to the heavens - and drink a toast to you every time I used it.

Bob M

Stanley,and comes with a lifetime Warranty