I'll be travelling from the UK to Hungary, and I was wondering whether I could bring two reusable hand warmers (the crystallisation type ones, like these) onto the plane, preferably as a cabin baggage. As they would be gifts, they are in their original packaging, but I'm not sure whether they would consider them fluids (I also don't know whether they are <100ml or not, they seem to be around the limit), or whether they would ban them outright, as they can activate accidentally therefore they might pose a fire risk.

I have found this TSA blog, they say it's okay, but that link is for US flights, and it also doesn't mention whether it would be considered fluid or not. I haven't found anything for EU flights.

  • Once crystallized, the device is no longer liquid. Activate the system before going through security.
    – Gusdor
    Feb 3, 2015 at 10:17
  • I have the same issue. Can't I just solidify them beforehand? They solidify and remain so until they are placed in boiling water. So, as a solid, surely they don't even come under scrutiny.
    – Will G
    Dec 8, 2017 at 10:38

1 Answer 1


Actually, while you're saying you're in Europe and have linked to the TSA Blog, the answer is actually there, if you read between the lines:

Crystallization – This is the type that you flex or squeeze to activate. They contain liquid and require adherence to our 3-1-1 guidelines. They can be packed in both carry-on and checked baggage.

SO the key thing here is that they contain liquid. Naturally, this means they're subject to any airline regulation regarding liquid.

From the European regulations:

Liquids carried in the aircraft cabin such as drinks, toothpaste, cosmetic creams or gels must be carried in a transparent plastic bag - maximum capacity 1 litre - and no container may hold more than 100 ml. Liquid containers larger than 100 ml must be placed in checked baggage. The volume restriction does not apply to medicines and baby food.

So your best bet is probably to put them in a clear bag like every other liquid you have, and when/ if questioned, explain there's a small a mount of liquid in the gloves. To me it's less than 100ml (I've used them before) but they may want proof, in which case you may want to find the spec sheets for your specific gloves to bring along to show that it's merely 40ml or whatever.

If you can show that, then by law, you meet the legal requirements, and you'll be permitted aboard with them. The spec sheets will also show that it contains merely sodium acetate (like baking soda and vinegar), but it's the ml that will convince them, I suspect.

You may still get someone who still doesn't trust them, in which case you may have to lose them or check them in the hold, so get there in time and allow for this.

  • 8
    Sodium Acetate which is the active agent in this hand warmer is not categorized under dangerous goods. I hold a license for dangerous goods identification, and I just checked the manual and found no mention of it. Your answer is right as long as the hand warmer has a label indicating the amount of the liquid... Feb 2, 2015 at 22:36

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