UKC

While reading the current thread 'what's in you're flask for a big day out' I realised that I don't have a flask anymore. We used to have a couple of Primus flasks, but they were useless; Luke warm drinks by lunch time. So, any recommendations for flasks? Well insulated and/or light?

Thanks,

Andy

Thermos.

Seconded. I have a Thermos Ultimate 500ml for on the hill.

Apparently I was a good boy last year as santa bought me the 900ml model for Christmas. 

The main advantage is how light they are compared to other steel flasks I've had. Keep stuff hot for ages too!

I have used several different types over the last couple of months - Stanley, Hydroflask, etc. The only one that keeps liquids piping hot after 6 hours or so (IMO) is the Zo Jirushi. In all the others liquids are tepid after 4-5 hours.

Ten quid thermos from Tesco. Still pretty hot after 8hrs. I used to class it a luxury but I now think it's pretty much a necessity for winter climbing.

The thermos claim they keep stuff hot for 24 hours. Reading into that a bit they mean drinkable warm (64 Celsius) after 24 hours.

From experience, I'd say it's about right but I've noticed a few factors:

The 500ml flask isn't as good as the 900 ml as there's less heat energy in the system versus similar heat loss to the surroundings.

Drinks like hot chocolate with high fat contents don't stay as warm as watery drinks like tea, ribena etc as the heat capacity of fat is lower than water so they cool much quicker.

The Thermos Ultimate are about the best I've used. Reasonably light and keep stuff hot for a full day on the hills.

In winter I regularly make three flasks the night before going winter climbing. I'll do this normally last thing so say between 23-2400. I'll have coffee in one, maybe two - the little 500 ml ones, both €5 from IKEA. I put tea in the big 1 ltr flask, on sale £3.50 from Asda. I drink one coffee as I'm driving the 3 hrs to the mountains. That will be scalding hot still 5-6 hours later. I'm might also have a cup or two from the big one on the way or as I park and get packed once there. I take one unopened flask with me on the hill. Last weekend I drank some as we put our harnesses on below the route. A bit more at the first belay and there was still some warm coffee in it as we topped out - maybe 1430?

When I get back down to the car I can have some tea from the big flask, even by early evening this is still warm even if not piping hot.

I reckon people who say these expensive flasks don't work either don't prime them or aren't putting hot enough drink in them! My oldest IKEA flask must easily be  decade old, has been chucked in packs and generally abused loads and still works better than some of the descriptions above.

??

I've a small Thermos & my partner a similar size flask from Ikea which cost much less, maybe a third of the price (& is a more attractive red). If I fill both of them at the same time, after pre heating in the same way, the Thermos stays much hotter for longer. But I suspect part of the difference is due to the stoppers as the Ikea has to be more open to pour than the Thermos. But my older, but much larger flask (around a litre) from, think, Alladin keeps water hotter than either, no doubt due to its size

Agree - big flask are more efficient than small ones, and stopper design must also make a difference. Mine all have pop up ones, I think simple screw caps might be better. Not letting your flask fall on its side seems to make a difference too.

I think it's down to expectations. I don't mind a brew not being scalding hot but others hate it.

Zojirushi flask. It keeps drinks warmer for many hours longer than most - particularly good in the cold. It's not cheap, but it's near bombproof and works a charm.

You can read the wirecutter review here: https://thewirecutter.com/reviews/best-travel-mug/

People's hot drinks in flasks going cold have always baffled me. I use a stanley flask most days which I got as a leaving present from work a number of years ago but cheap flasks don't go tepid any quicker. Basic rules are

1 - preheat the flask (doing this twice will work better for obvious reasons),

2 - the bigger the flask the longer it stays hot,

3 - a full flask will stay hotter for longer and

4 - if it's not boiling hot when you fill it it wont be boiling hot in 10 hours (i.e. don't put cold milk in and expect it to rise in temperature by the time you're drinking it)

My 500ml stanley will give a hot drink 12 hours later (i.e. burn your lips hot), on occasions where I've forgotten it at home it's still been drinkably warm the next morning. My experience has always been the same with cheap flasks.

If you like hot tea and brand names then go zojirushi or stanley, if you just want hot tea then go to tk max.

I have a Thermos, my friend a Stanley.  Both work great, and I can attest to the durability of the thermos - it really can take a beating.  

That said, the Thermos has a narrow and tall opening which makes cleaning difficult (not impossible) and the shape of the screw in bung is difficult to operate and not friendly to tired + cold fingers (Two things I didn't consider when purchasing)

Another vote for a thermos, think mine is 700ml. Works grand.

Got a 300ml Lifeventure one too which is fine, but is probably less efficient due to aforementioned reasons of thermal mass and surface-to-volume ratios.

If I'm honest I usually carry the latter on the hill because it's lighter and I never finish the big thermos when I'm out and about.

I don't seem to be able to post the link but if you go onto The Song of The Paddle, website & Forum and search for "Vacuum flask reveiw", you should find a comprehensive  test of a number of differing models/makes.

500ml Lifeadventure is fairly rubbish. We've even tried wrapping it up in a belay jacket and the damn thing still doesn't stay warm.

Thermo-dynamics says size matters.  

FWIW, Trail magazine does reviews of flasks, the latest I can seem to find is Oct 2016

Scan: https://photos.app.goo.gl/Va7wilbxeragxh4s2

Allan (no connection with said publication other than as a reader).

Presumably the rate of cooling will accelerate as you use it throughout the day and the liquid within the flask becomes replaced by more and more air?

Thanks very much for everyone's input. I reckon I'll get a Thermos Ultimate, and make sure I preheat it!

I guess if you open it in really cold air, that is the cold air that will get in and cool your drinks faster.

What we need is a flask that has two compartments, one with the hot fluid, and another with hot air, as the fluid is poured out through a small nozzle, the air is then replaced from a breather tube directly connected to the hot air chamber, which will expand through and into the now opened breather tube, and into the void in the flask  left by the fluid poured