Review of 1 pint (0.5L) vacuum flasks
We put boiling water in vacuum flasks from a wide range of manufacturers, left them for several hours and then measured the temperature. The winner was Zojirushi SV-GG50-XA followed a close second by Thermos Ultimate Insulation.
Temperature of the water from boiling after 8 hours:
|Zojirushi SV-GG50-XA||172 F||78 C|
|Thermos Ultimate Insulation||171 F||77.5 C|
|LaPlaya High Performance||168 F||75.5 C|
|Alfi isoTherm Eco||167 F||75 C|
|Aladdin Fundamentals||167 F||75 C|
|Primus C&H Vacuum Bottle||166 F||74.5 C|
|Stanley Classic||163 F||73 C|
|Emsa Senator||161 F||71.5 C|
Smaller flasks normally get cold more rapidly because they have more surface area to volume, so the flasks we tested were all 1 pint (0.5L) capacity. We warmed the flasks with boiling water, emptied them, filled them with boiling water, and left them in a room at 59 F (15 C) for 8 hours. All of these flasks are stainless steel.
This is an elegant, compact flask with a non-stick lining. Unfortunately, like all the flasks we tested except the Primus C&H flask, it is not dishwasher safe. Manufactured in Thailand for the Japanese company Zojirushi.
Thermos Ultimate Insulation
The Thermos is made in Malaysia for Pacific Market International and comes with a 5 year warranty.
LaPlaya High Performance
Alfi isoTherm Eco
Made in China. 2 year garantee.
Made for Pacific Market International.
Primus C&H Vacuum Bottle
This was the only dishwasher-proof flask in the test. It is made in China. There are two stoppers - one to pour the contents without unscrewing the stopper and the other for better insulation. We tested it with the better insulation stopper.
This flask has a large cup and a 25 year guarantee. Made in China.
We had high hopes for this sturdy and good looking flask, but sadly it did not retain the heat well. Made in Germany and comes with a 5 year garantee.