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Thermos with 100% metal cap?

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  1. #1

    Thermos with 100% metal cap?

    Hi,
    I've checked dozens and dozens of thermos bottles from different brands. They all have plastic in their caps, either parts of it or simply fully made of plastic.

    We've had a few and after some time the plastic starts decoloring, falling off etc. So we end up with plastic in the water.

    Anybody knows a thermos with a cap that is plastic free? Can't believe I can't find a single one. I check every time I go to a shop that sells thermos -- never seen one so far. Not a single brand realises that boiling water vapors will eventually brittle/melt the plastic cap?

    thanks


  2. #2

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    I get my all metal flasks from Amazon, cheaper than buying decent ones here.


  3. #3

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    Quote Originally Posted by Castlevania:
    Anybody knows a thermos with a cap that is plastic free? Can't believe I can't find a single one
    Get an insulated Klean Kanteen. It's worth the money.
    Elegiaque likes this.

  4. #4

    The Zojirushi in the link has a plastic cap, like all the others. The body may be metal or glass, but the cap is always in plastic -- partly or fully. Yes I've been to different Sogo and Yata shops. Caps always in plastic, even for the most expensive models.

    Will have a look at the Klean Kanteen, thanks.


  5. #5

    Yeah that brand gets it, they even have caps for sale separately.

    But why do they say they're not meant to be used with hot liquids? I thought that was the whole point.

    "The Steel Loop Cap is leak proof and creates a 100% stainless environment inside your bottle. Made from 18/8, food-grade stainless steel, threads included, your drinks never touch plastic. Dishwasher safe. Compatible with Classic Klean Kanteens only. NOTE: not intended for use with hot beverages."

    https://www.kleankanteen.com/product...nless-loop-cap


  6. #6

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    Quote Originally Posted by Castlevania:
    Not a single brand realises that boiling water vapors will eventually brittle/melt the plastic cap?
    Firstly, how you seal metal on metal? It's possible, but very difficult. Metal isn't that suitable as thermal insulator anyway.

    The max water temp is 100°C - at that temperature nearly all plastics are still stable. The cap base ist what? ABS, Polycarbon (PC), Nylon (PA)? That can handle 200°C or more.

    Talk about the sealing, you need something softer - that is usually silicone, that can handle up to about 230°C before it breaks down.

    In reagent chemical bottles the sealing is usually PTFE due its high temp and inert capabilities, that can withstand up to about 280°C.

    BTW, an all metal thermo would be perfect to keep anything at ambient temperature for long time.

  7. #7

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    Thermal vacuum flask based on entirely metal material would not keep liquid inside warm/cold because metal are all good conductor of heat.. heat will be transferred in or out.. you need to have insulating material like - vacuum, rubber, plastic, etc.etc.etc.. So it is extremely difficult to make a cap with no plastic, entirely metal, for a thermal because then they would need to put in a complicated vacuum layer in the small cap just to trap the heat in..

    If the OP is only referring to the external layer, then there are tonnes (e.g. the tiger or zojirushi ones).. if you are looking at the entire cap in metal with no plastic.. i really don't think its scientifically practical/feasible


  8. #8

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    The Kleen Kanteen tops use a silicon o-ring to stop leakage


  9. #9

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    Quote Originally Posted by GeoTommy:
    Get an insulated Klean Kanteen. It's worth the money.
    I second Klean Kanteen. They have some plastic-free options.

    Being an American company though, they do have some design issues. But overall excellent products and the water always stays very fresh.

  10. #10

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    Original Post Deleted
    Yes, they all do. I was responding to what I interpreted as a post that implied that they only use steel. Which would not be workable.

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