I have a pretty standard hand warmer with the metal discs in them to activate them - I did some research and found out that they are Sodium Acetate hand warmers and the disc is used to 'freeze' the liquid making it heat up.

I used this on the way to work as I was getting a little chilly and now that I am at work I want to 'recharge' it, i.e. make it back into liquid form, and the instructions given for doing this is to put the pack in a pan filled with boiling water and then allow it to simmer for 10 minutes and it should be returned to it's original state.
However, as mentioned, I am at work and unfortunately we do not have a stove for me to keep a pan simmering for 10 minutes but I do have a microwave and a kettle and other standard kitchen utensils. So my question is, is there a lifehack / way to 'recharge' / reset a sodium acetate hand warmer without having a stove to keep water simmering for 10 minutes? But instead just using standard utensils or a kettle or a microwave?

Note: It does say on the pack not to microwave or put it in a kettle but if there are any lifehacks contrary to these warnings, I am not afraid to be a bit of a 'Daring Dan' and break the rules because sometimes I just want the world to descend into anarchy.

  • 1
    If you boil some volume of water in the microwave then put the hand-warmer in, would that work?
    – Nick T
    Mar 16, 2015 at 19:06
  • 1
    What ever you do, I say this, do not microwave it. It's dangerous even on a low setting.
    – user12556
    Feb 23, 2016 at 14:45
  • Just. Dont. Do it. Dont be a statistic. Thats a blessing of the internet. Before we make ourselves a statistic, we can look it up, find out by other peoples mistakes what not to do, etc. Go see what happened to other folks on youtube! Goodluck and God bless.
    – Ms. Hood
    Jan 28, 2021 at 12:09

10 Answers 10


I think the kettle advice is just so it doesn't get into contact with the heating coil.

I have a kettle that has a covered coil and it works fine with those, but you have to keep it in there for a while (it still needs a few minutes to completely dissolve, there is no instant solution).

Due to inequal heating in most microwaves I would not recommend this, but I don't see anything that should inherently make it not work, other than the piece of metal in it making it somewhat dangerous.

If you are that daring dan type and have one of those handwarmers that you don't need, along with a microwave that you don't need I would give it a try and do it on low power settings. The worst that can possibly happen is it popping open and covering your microwave in sodium acetate.

  • Note that there's nothing wildly dangerous about microwaving metal. The first microwave cookbooks even had instructions about how to use aluminum foil to let you cook foods that required different temperatures simultaneously. It does require understanding how a microwave works though because shape and orientation of the metal make huge differences in how hot it gets and how fast. For these heat packs the problem isn't the metal. The metal is submerged and will dissipate the heat fast enough. But if you overheat the pack, even just a little, the steam pressure will burst it. It's quite touchy.
    – Perkins
    Mar 16, 2019 at 23:43

Heat up water in kettle or microwave . Pour hot water into s bowl, and place Hester into hot water. It won't take 10 minutes. Make more hot water and add it to bowl as necessary to keep the water in there hot.

Under NO circumstances should you put your heater in the microwave! The metal disc will start arcing and destroy microwave!.

The reason they tell you not to put heater in a kettle, is so that the plastic bag doesn't get melted against the hot metal surface in kettle. You can try to "suspend" heater bag in kettle, so that it doesn't actually come in contact with the kettle's interior. Or you can wrap your heater in a cloth rag before dropping it into the kettle's water. Rag with keep plastic bag from touching kettle's hot surfaces, which is hotter than the water.


I find kettle boiled water poured over a single hand warmer in a jug is effective, just a couple of minutes.

  • They said they don't have a stove available
    – L.B.
    Oct 10, 2016 at 13:04
  • 1
    @L.B. They do, however, have a kettle available. Electric kettles are much more common in the UK than stove-top kettles.
    – owjburnham
    Feb 25, 2019 at 8:08

I have put a hand warmer in my tea mug and used the Hot water feature on the tap that is connected to the coffee maker and it took about 12 minutes if I poured the hot water over the bag while it was in the cup and then put the lid on. Worked fantastic, was warm from that for almost an hour and then activated it after that again.


You could make a stove out of some candles, find something to hold a bowl above them, fill the bowl with hot/boiling water and that should fix your problem.


So first fact's first. Almost (almost) everyone knows you don't put metal cutlery and foil in the microwave. Why? "IT'LL EXPLODE!" well. No. What happens is... Well, I'm not an engineer or particle physicist but it basically polarizes the particles in the metal, I researched it one time for a short story I was writing. I can't remember which but I feel strongly that the correct word is ions... The point however is that this is a problem on things with ridges. Foil is a problem because of ridges. Forks are a problem because forks. Basically the sparking you're seeing is electricity formed by that polarized flow of particles arcing between ridges. If the disk inside the hand warmer is flat metal, you're fine, if it, like mine, has ridges in it, you might want to think twice. That said, you should probably drop the thing in a bowl of water first, nuke for 1 minute, check, then repeat until the fluid is clear, any arcing that is caused will damage the product, not the device... Though you may potentially burn your self or make a mess if you aren't careful. Discretion is always the better part of valor but the truth is you stand a better chance of overheating the metal disk and melting the container or overheating the liquid and causing the sealed container to pop than you do of blowing up the microwave.

Special note. Only ridged metal "arcs" but the polarization of...again, the correct term eludes me but ions sounds right... Is present either way, metal does get very, very hot when exposed to microwaves. Even if it doesn't cause arcing. Which, unless you like third degree burns, is why you should not put plates with metal accents in the microwave.

There is however a better way than most listed. You may have to go through amazon but there is a device intended for use with wax scented candles. It's a heating plate. Idea is you place the jar on the heating plate to release the scented oils. They've fallen out of use hence why I suggest Amazon rather then wasting time searching stores. I've tested this my self. Lay the crystallized hand warmer on the heating plate for about an hour, you have plenty of time to activate multiple hand warmers over a standard eight hour work day, after about an hour the fluid will be clear and ready for use. Better, it will be hot. Not instantly burning your skin hot, more like hot wax hot. And it retains that heat for around 30 to 45 minutes. Meaning you can use one hand warmer for almost twice the time by taking it fresh off the hot plate, dropping it in a pocket don't do this if it's a pocket against bare skin, prolonged exposure may cause minor burns and you're good to go, after it cools down, a certain level of cooling may or may not be needed for reactivation... Just snap the plate and it's good for another half hour. Obviously this only works if you have private access to a power plug.


I finds that a bowl full of boiling water works by just dropping it in Andy leaving it there for 5-10 minutes. My personal one is quite old so takes about 12 minutes but if yours is relatively new it shouldn’t.

Hope that helped!

  • That answer has already been given
    – Chenmunka
    Sep 13, 2018 at 15:26

I place a sheet of paper on my coffee cup warmer, then the heat pack on the paper, then fold the paper over like a blanket over the heat pack. Let it sit there for 30 or 40 minutes, mix the liquid and the crystals occasionally and re-position on the warming plate. After a while all the crystals melt and its ready to reuse.


Does your work have a standard coffee pot? If so you can warm water up to a boil in that and then pour the water in a thermoses then place the hot pad in side your thermos to keep it hot for ten min.

This was a brain blast hope you find a Solution


Heating sodium acetate hot packs in a microwave does in fact work. The metal disk is isolated from any other conductive items so the microwave energy has no effect on it. Do beware the uneven heating of some microwave ovens though.

  • That is quite a general statement you're making. Do you have any proof this applies to the general case?
    – holroy
    May 11, 2017 at 7:49
  • The moment I hear microwave and metal in the same sentence, alarm bells start going off in my head. This sounds like a recipe to burn your house down, or at least destroy the microwave.
    – L.B.
    Feb 25, 2019 at 13:18

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