Primus – Lunch Jug 0.35L

Shelf appeal. That’s what this chunky little Lunch Jug has. With it’s bright colours and ‘touch me’ matt texture I can’t remember how many times I’ve spotted it in a shop and just had to pick it up.

And it feels great in your hand, with a reassuring solidity and toy-like familiarity that are easy to hold when you’re cold and wet.

The Primus Lunch Jug 0.35L is designed to keep your lunch separate from the rest of your belongings, insulated so it stays either warm or cold, and be easy to eat out of. And it scores brilliantly on two out of three of those points.


It has a widely spaced screw thread and O-ring combination top which seal very easily and don’t require He-Man proportions of muscle to open or close successfully. A vigorous shaking, rolling and chucking around the garden proved to me that once shut only the desire to open it would reveal its contents and my clothes in my pack would be safe from the odour of chicken soup.

The top is very slightly detailed with ridges to make it easier to open when your hands are cold and wet, and these work OK. They’re not the deepest knurls, but they do make a difference.

The wide mouth of the smaller of two Primus Lunch Jugs is the same internal diameter as a tin of soup, so it’s easy and straightforward to get your fork or spoon in to, and the gently radiuses bottom means you can fairly easily scrape out the last drops of food. It also makes for a very easy combination to clean.

I pre-heated the Lunch Jug (as you should with any insulated vessel) and popped in a tin of soup for my lunch one day. Slightly annoyingly, the tin of soup (Heinz Cream of Chicken) said 400g on it and there was a little bit too much soup for the Lunch Jug. The soup came up to the top of the insulated silver inner and when I screwed the top on it was forced up and out of the screw threads. This’d be something to bear in mind if you planned to use it for tinned soups regularly, but not a problem if you have home-made soups or other food that doesn’t come in pre-made portions.

I was surprised by how much the temperature of my soup had dropped within 4 hours. I think I was expecting the same levels of insulation as in a Thermos vacuum flask but wasn’t getting them. I decided to run a more scientific test at home to give some indication of performance.

I poured in freshly boiled water to the top of the Lunch Jug and measured the temperature at 95C. I sealed it up and left it in my kitchen at an ambient temperature of 20C for 4 hours, then re-measured the water temperature. It had dropped to 58C. I’d imagine that if you had the Lunch Jug filled with piping hot soup and went for a walk on a cold day, you’d be slightly disappointed with the lack of piping when you settled down for lunch unless you wrapped it in your spare clothing. Perhaps my expectations were too high?

SUMMARY: The Lunch Jug from Primus is a chunky, rugged little vacuum flask that will keep a hot lunch ‘hot’ for around 3 hours and then ‘warm’ for several more. It has a very solid and easy to open seal and is easy to eat and drink from. It has a great feeling in your hand and is pleasant to grip even when you’re cold and wet. You might not get an entire tin of soup into it though.

 Price: £15
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