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Filling outside of Flask with some sort of insulation

Posted: Wed Sep 16, 2015 2:49 am
by 500N
Would like to call on the collective wisdom of those on here.

I needed a new Mug that fitted in the car cup holders and for what was the same price
as a mug only, I could buy a 2 mug and Flask set. Flask is 500ml.

As expected, flask isn't that good at keeping coffee hot for long period, at least not like
the thermos of old that kept things hot for ages. I have a larger flask that is much better
but too big to use all the time.

Vaccum / Insulation ?
Although they say it is insulated with a vacuum between the inner and outer steel,
I have my doubts.

So, was wondering if it's worth drilling a hole in the bottom and filling the gap
with some sort of liquid, expanding insulation or powdered charcoal (I believe
they used charcoal in the past). I would expect cost would be less than $5 to do
but if I do it, I want to make sure I pick the right product.

Any thoughts ?

.

Re: Filling outside of Flask with some sort of insulation

Posted: Wed Sep 16, 2015 3:56 am
by John Hill
I really dont know how anyone can go through life without knowing how to make a vacuum flask.

The process is very simple.... drill a small hole in to the 'vacuum' space and put several drops of water in there. Heat the flask until the water is driven off as steam and as soon as the steam stops solder the hole closed.

Re: Filling outside of Flask with some sort of insulation

Posted: Wed Sep 16, 2015 5:29 pm
by probes
Me, being a bit afraid of drills and chainsaws - happy with that:

Image

especially for drink&driving. Won't keep it warm forever, I guess, but long enough and comfortable to drink (which is not the case with all thermo cups).

Re: Filling outside of Flask with some sort of insulation

Posted: Wed Sep 16, 2015 5:55 pm
by Fox3WheresMyBanana
The best mugs I have found are Contigo. They have lots of imitators now, but those are only about half as good.
Contigo claim 4 hours hot, and I can confirm that after leaving a full cup for a morning.
In practice, taking regular sips, the last mouthful will still be acceptable after about 2 1/2 hours. That drops to about 1 1/2 hours for the competitors.
This has been tested in the cupholder on my lawn tractor, used as a snowplough, in minus 20 Celsius.
Every one I know has them now.

The Thermos brand 1L stainless steel flask is the one to get. 8 hours hot it claims (I've tested it to 6, check), and will last forever.
Going smaller than 1L is never going to work as well from the basic physics, (volume/surface area ratio and all that)
Much of the poor performance of cheaper brands is down to the lid/cap design, not the main chamber. The vacuum process is pretty cheap,so that's unlikely to be the source of the problem.
I wouldn't waste your money on anything other than Contigo and Thermos.

From the land of coffee addicts and 18 feet of snow.

Re: Filling outside of Flask with some sort of insulation

Posted: Wed Sep 16, 2015 6:01 pm
by rgbrock1
Behold the 'Silver bullet'. Used to keep coffee hot for hours.

Image

Re: Filling outside of Flask with some sort of insulation

Posted: Wed Sep 16, 2015 6:44 pm
by 500N
Fox3
Yes, have heard of Contigo. Luckily we don't have -20 and 18 ft of snow but would invest in the top stuff if we did.
I just checked my two "big" flasks, they are Spectrum and although not as good as Thermos
they lasted me for years and I used them often in the mil in Winter.
Thanks for your comment re the cap/lid design. I think you might be right.

We had Thermos in the UK, I remember breaking a few of them :D

RGB
Looks the goods !

John
Thanks for the input.

Re: Filling outside of Flask with some sort of insulation

Posted: Wed Sep 16, 2015 6:54 pm
by Fox3WheresMyBanana
I remember breaking a few thermos ones in the UK also - they've improved.
The handle design makes me think RGB's is a rebadged (new) Thermos.

Re: Filling outside of Flask with some sort of insulation

Posted: Wed Sep 16, 2015 7:00 pm
by rgbrock1
Fox3WheresMyBanana wrote:I remember breaking a few thermos ones in the UK also - they've improved.
The handle design makes me think RGB's is a rebadged (new) Thermos.


Dunno. The 'silver bullet' I carried with me as if it was a third arm, was indeed a Thermos. The photo I provided above seems to be a newer model as the ones we used had slightly different handles.

Re: Filling outside of Flask with some sort of insulation

Posted: Wed Sep 16, 2015 7:01 pm
by 500N
I think you are correct re rebadged.

Edit
RGB beat me to it.

Re: Filling outside of Flask with some sort of insulation

Posted: Thu Sep 17, 2015 4:53 am
by John Hill
500N wrote:
John
Thanks for the input.


Dont mention old chap. As far as I know the process is kosher.

Re: Filling outside of Flask with some sort of insulation

Posted: Thu Sep 17, 2015 5:33 am
by Happy SLF
https://www.pregoli.co.nz/extras/551-co ... l-mug.html

According to website they will send to Australia, you can swap country from NZ to Aust and then they give
prices in $Aus but ship goods from here.

Re: Filling outside of Flask with some sort of insulation

Posted: Thu Sep 17, 2015 3:41 pm
by Fox3WheresMyBanana
That's about 4 times the Canadian price! (C$25 for two from Costco).

Re: Filling outside of Flask with some sort of insulation

Posted: Thu Sep 17, 2015 3:44 pm
by 500N
Fox3WheresMyBanana wrote:That's about 4 times the Canadian price! (C$25 for two from Costco).


That's normal for Aust and NZ.

Re: Filling outside of Flask with some sort of insulation

Posted: Fri Sep 25, 2015 5:06 pm
by 1DC
500N I have a flask that looks identical to yours, i bought it three months ago. I fill it with boiling water from the kettle and leave it for ten minutes,then empty it and put my coffee in. Six hours later the coffee is still hot, so i was impressed with the product. Having said all that you flask experts may think that is a poor performance but as this, after 75 years on this earth, is the first and only flask i have ever owned i may be a very inexperienced flask owner..

Re: Filling outside of Flask with some sort of insulation

Posted: Sat Sep 26, 2015 1:18 am
by 500N
Well, I did a test.

Two flasks, one warmed up before filling, one not.

It made some difference.

Anyway, I have my two big (good) flasks so can always use those.

Re: Filling outside of Flask with some sort of insulation

Posted: Sun Sep 27, 2015 8:27 am
by OFSO
If it's keeping fluid hot* you want and in a car, put the flask in the engine compartment near the exhaust manifold or in diesel cars near the turbo. N.B. Not if you own a diesel VW and live in Switzerland.


* Cher is reputed to have responded to a question relating to which is the most remarkable invention of mankind, "the vacuum flask - because how does it know when you want to keep something hot OR cold ?"

Oldy but goody

Posted: Sun Sep 27, 2015 1:56 pm
by 19downbubble
David Beckham gets a birthday prezzy from his wife.

"What's that?" he asks. "A Thermos flask," she replies. "What does it do?" asks Becks. She tells him it keeps hot things hot and cold things cold.

Really impressed, he takes it along to his next training session.

"Here, boys, look at this," Beckham says proudly. "It's a Thermos flask."

The lads are impressed. "What does it do?" they ask. "It keeps hot things hot and cold things cold," says David.

"And what have you got in it?" they ask.

"Two cups of coffee and a choc ice."

Re: Filling outside of Flask with some sort of insulation

Posted: Mon Sep 28, 2015 9:00 pm
by sprintman
Spray cans of insulating foam available Bunnings etc.

Re: Filling outside of Flask with some sort of insulation

Posted: Wed Sep 30, 2015 6:53 am
by Hydromet
Spray cans of insulating foam available Bunnings etc.

Bear in mind that this stuff sticks to anything like ***** to a blanket. Also, it will expand whether there's room to or not - it will make its own room. If you spray a little water into the void before the foam, it speeds up the expansion. For your flask, you won't need much foam sprayed in.
Should do the job.

Re: Filling outside of Flask with some sort of insulation

Posted: Fri Nov 27, 2015 10:30 am
by Lon
amazing things flasks. How do they know to keep cold things cold and hot things hot?