Our panel included sport enthusiasts Dean Taylor and Sue Bradford; keen amateur cook Philippa Yeoman; company director Rhys Jones; and hill walker Stephen Sykes.
British Standards award stars for the length of time taken for food or liquid within a container to fall from 95C to 75C. As an approximate guide, one star means you can rely on the product to keep its filling warm for 1-2 hours; two stars 2-4 hours; three stars 4-6 hours; and four stars over six hours. Not all manufacturers subscribe to the test. We did our own testing, which allowed for kitchen, rather than laboratory conditions. "For best results", as they say, you should heat the container with hot water first - fair enough. But the container should also be completely full - not always possible. The greater the mass, the longer it takes for a substance to cool, so small flasks are generally inefficient. Other criteria included style, weight and, inevitably, branding.
**THERMOS 'WEEKEND' FOOD FLASK
1 litre pounds 9.49, 0.5 litre pounds 7.49.
These are the flasks we all remember from childhood, with a breakable glass liner and jolly plastic covering in the "bright, appealing colours" (brochure) which seemed "pretty naff" to our panel, half of whom took an instant dislike to them. They are lightweight and feature a new, wider- mouthed format for soups and stews. But the plastic inner lining retains smells and you get what you pay for when it comes to heat retention: after six hours, the large one fell from boiling to 69C (drinkable) and the small one to 57C (warm).
**THERMOS SENTINEL STEEL FLASK
1 litre pounds 24.99, 0.3 litre pounds 17.99.
The "hip flask" from the ads. Unbreakable, stainless steel, more affordable than exotic equivalents and shaped "to fit in a briefcase", they have a pour-through stopper and insulated cup. The panel thought the design a definite improvement on Thermos's own cheaper versions. It was Dean Taylor's favourite; "It's got to be Thermos, hasn't it?" The larger version, which fell from boiling to 82C over six hours (excellent) would have merited a four-star rating. The low rating reflects the hopeless performance of the small flask, which dropped to 44C.
**ZOJIRUSHI THERMAL LUNCH JAR
This oriental-style insulated canister for hot food has three different inner containers (for soup, rice and perhaps fish), a nylon carrying bag and chopsticks in a hinged container. It was greeted with squeals of delight by the female panel members, who awarded it ten out of ten "for dinkiness". But heat escapes through the lid, leaving the top container at 41C, the middle at 65C and the bottom at 67C after three hours. Philippa Yeoman said she would continue to use it nonetheless; it impressed her colleagues, who already think her quite a gourmet.
***ALADDIN 'STANLEY' 0.95 LITRE VACUUM FLASK
Just as Thermos is the number one brand in Britain, Aladdin is the bestseller in the USA, and this unbreakable, BS four star, stainless steel flask with hammered green covering is a classic in their range. Its "toolbox" looks appealed to Dean Taylor and Stephen Sykes said this was the flask which had survived being run over by his father's tractor - pretty impressive. Other, more delicate panel members worried about its weight and height: it inconveniently "stuck out of the top" of Philippa's rucksack. After six hours, the temperature of the liquid fell from boiling to 80C.
*****TUFFBOY 1 LITRE VACUUM FLASK
Made in Japan but with conspicuous American styling, the hilariously macho name of this unbreakable, stainless steel flask caused initial giggles, but usage proved it the outright winner in our test. An insulated lid which locks into place with a button, a flip-up spout for pouring, a handle which folds flat against the casing and a removable carrying strap were the concrete features which impressed the panel. These were summed up by the general feeling that the flask is "beautifully made" and "everything clicks into place so neatly". It also had the best heat retention properties, falling after six hours from 95C to 86C (still hot enough to brew a fresh cup of tea).
***VANGO 1.2 LITRE STEEL FOOD FLASK
This nicely designed Scottish flask illustrates the current trend for unbreakable stainless steel, but with a wide mouth for carrying soups and stews. It has a detachable carrying strap and the women preferred the look of the Vango to the Tuffboy, but it didn't perform so well - its temperature fell after six hours from 95C to 78C.
***FLECTALON PICNIC GRIP
This zip-up, insulated bag relies on space technology - the reflection of heat by fine reflective fibres as developed by NASA - beneath a wipeable plastic lining to keep your take-away piping hot or allow you to transport hot food to your log cabin (or, in our case, allotment shed). It has a BS three-star rating, but it has to be absolutely full; in practice, when you stuff some crockery and a vacuum flask at one end, the temperature falls from 95C to 63C after three hours - still edible, comforting in a stiff breeze. The handles are exactly the right length to carry the bag on your shoulder, leaving both hands free "to hold onto the kids", as Sue Bradford put it.
Aladdin 'Stanley', Boots; Flectalon Picnic Grip, John Lewis; Tuffboy and Zojirushi info/mail order from Elia International, 0181 997 7368; Thermos from department stores; Vango stockists info from Vango Scotland, 01475 744122. !Reuse content