None of the ones I've tried have performed as well as glass ones. At best SS ones keep things hot(*) for only a few hours, the glass ones
12 hours+.(*) ie make coffee that is too hot to drink straight down.
I can't see how steel ones can possibly work as well as glass ones when there is metal/metal "bridge" between the inside and the outer case which must surely conduct heat faster than the glass/plastic/metal construction of a conventional flask.
Tim
I've used SS ones for years and found them exceptionally good. Certainly more than hot enough to drink 24hrs later. I did run a check on one a while back and I decided that there was just a little, a very little,leakage of heat at the top where the cap screwed in, but no where else.
Well I'm inclined to doubt this. As I have a SS flask and conventional flask both holding 1L I'm gonna fill them now with boiling water and report back tomorrow evening with my results.
Tim
I'm still using one that my mother in law bought 45 years ago. It's had a replacement stopper in the 90's, but certinly keeps the heat as well as it ever did.
Yes, that's usually what I used to do.
That's why I use Stanley SS ones now :-)
One of my SS Stanley flasks met an unfortunate end when I discovered that if you put the gun stabiliser in a Chieftain tank on you could put your flask on the gun breech and it wouldn't fall about the place as the tank moved cross country. Unfortunately what I hadn't realised was that if you then went up a steep slope the gap between the turret roof and the gun breech became much less than the height of the flask.
A lot easier if you don't need to open them up. On occasion I've been handed one which had disgustingly stinky liquid trapped - and no-one had ever seen fit to clean it. (Not mine, I speedily claim. My fault in this department is managing to smash the glass while cleaning the flask properly.)
Dammit man, you cannot just go and counter wild speculation with actual quantitative observations!
Look forward to the results BTW...
Unfortunately I am away for a few days as of tomorrow lunchtime, but I will do the same now and check in the morning.
I have to say it's not looking good for the SS flask. There's an easily palpable temperature gradient from the neck down where the heat is bleeding away. The conventional flask just feels at room temperature.
Tim
In message , Bill writes
I suspect that much comes down to the design of the neck/top as this is likely to be the potential weak spot with SS flasks.
We have a cheapy wilko one, that has quite a large area of SS neck which does get warm - from heat conduct up the inside, and down the outside I presume (the rest of the casing feels at room temp). The flask works well enough for what we tend to use it for - keeping hot enough for a few hours on a walk, But after say 12 hours I think it would be pretty cool
We have a different design of flask, Thermos IIRC which has a plastic kind of cap at the neck of the flask into which the stopper screws. And while I've never timed it I have noticed that drinks in it do stay hot for an appreciable time. I might have to fish it out and do a comparison
Agreed. One of my SS flasks is the replacement for one that didn't work when new. It was replaced by the shop, and both of them that I now have are still great.
From your description it sounds like there may be different designs of SS flasks available. I've never seen one though where the interior isn't bridged to the exterior with a metal/metal bond. Is this not the case with your one?
Tim
You may well be right but until someone explains how their flask is fundamentally different from my one (perhaps by NOT having a metal to metal thermal bridge to the exterior) I'm still inclined to believe that the traditional glass ones will always be superior for keeping stuff warm.
Tim
I agree that stopper design makes quite a difference. Our current ones (I forget which make/model but could be more recent Wilko) seem to keep the liquid well away from the brim. Seem better than our old ones (even when they were new) which over the years did appear to have compromised vacuum (the whole outer got slightly warm).
Have you got your results yet?
I will know when I get back later this week from my fathers funeral! The one that I destroyed by dropping it recently and putting a massive dent in it is due to be attacked with an angle grinder! But this will have to wait a while!
Right!
I filled my new one, from Argos and made by Thermos, with boiling water last night and now, 12 hours later, the water is still too hot to keep my finger in.
In message , Bill writes
Well, out of interest I filled the 1L I-don't-expect-it's-great-Wilko flask last night. And actually, it's better than I expected
After about 12 hours it's still plenty hot enough, it's at that just about as hot as I want to drink temp. I did stick a thermometer in, but it is one out of the aquarium and it only goes up to +70C. (So I'd say about 80C?, DMM with probe not where it should be, and I can't find any others without going outside).
I think that glass flasks may well have ultimately better performance, but that doesn't really matter to me, if a SS flask has good enough performance, and has the advantage of not breaking at inopportune times.
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