What Makes A Good Thermos?

A good Thermos is invaluable on a boat — whether for having a cup of coffee in the middle of a cold watch, keeping water hot for use later in the day or actually cooking in it.

And in my “kitchen counter” testing, it’s been clear that some brands and styles work better than others.  And that has left the question as to exactly what design features do the best job of insulating.

This morning I found the answer, in a chart put out by the Thermos company.  And it’s as I suspected — they key is having double-wall construction with a vacuum between.  Not air, not insulation, but truly nothing.

Everything in the table below rings true with my experiences using a wide variety of “insulated bottles” over the years.  The cheap ones with just air between two walls do little to keep anything hot.  Foam insulation is somewhat better (and was what we found almost exclusively in Mexico).  My glass-lined bottle works almost as well as my really good Thermos Nissan, but I’ve broken the glass on previous ones I’ve had.  And they are bulkier.  At the same time, while I love the top-of-the-line Thermos Nissan bottle and insulated mug that I have, the price for each made me wince.

My recommendation is to go ahead and get the stainless vacuum bottles.  Short of going over one with a steam roller, they’re indestructible and they’ll keep drinks and food so much hotter than any of the other options that they are really worth it (particularly if you want to do any Thermos cooking).  The supposedly cheaper ones I’ve bought have just cost more in the long run as I got fed up with them, got rid of them, and upgraded.

I love the Thermos Nissan ones.  They’re not sold in the small town I’m in (they have plenty of the cheap ones at the stores here!) but Amazon has a variety of sizes and shapes — see them all here.

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  • Steven K. Roberts
    Posted at 03 August 2013 Reply

    As the old story goes, the thermos bottle is the greatest invention ever. It keeps hot things hot, and cold things cold. BUT HOW DO IT KNOW? 😉

  • bob carignan
    Posted at 01 September 2013 Reply

    It’s not the bottle it’s the stopper. They change the style of the stopper into a “click/pour and seal. It’s designed so complicated and poorly that its impossible to clean. I have tried everything. It unscrews into two pieces, but both part are so complicated with small nooks and crannies that after some coffee usage a slime gathers in these minute spaces and starts to rot and smell. It gives the coffee a very unpleasant taste. I have used “Thermos” brand for over 60 years and they have always had a great product. They better take a close look at this stopper. It’s very unsanitary and unhealthy. Please inform them.

  • mary
    Posted at 08 August 2014 Reply

    I want to purchase a Nissan wide mouth and a one quart. I can not find out what type of plastic is used on the inside lid area. Is it PVC free. Can you tell me?
    I have their large thermos cooker and really love it.

    • Carolyn Shearlock
      Posted at 08 August 2014 Reply

      I called the Thermos Customer Support line (Thermos is the parent company of Thermos Nissan) at 800-831-9242, and the woman I spoke to said that all of their products are PVC-free in areas that would come in contact with food or drinks.

  • Jay Martin
    Posted at 30 October 2015 Reply

    …my daily companion.

  • Nancy Nazar
    Posted at 30 October 2015 Reply

    Many many years ago, when traveling to China to adopt my first daughter, I bought a stainless steel Nissan. Had that thing for 20 years and my daughter has it now. What sold me? The fellow at the outdoor store who sold it to me, brought out his own at 4pm in the afternoon and poured out piping hot coffee with which it had been filled at 6am! They are fabulous and indestructible!

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