Instructables
Have you ever gone to a football game and frozen your butt off?   While at the game you happen to have brought those little charcoal throw away handwarmers.   You pull it out, open it up, and shake the daylights out of it trying to get it to produce some heat.   Normally the amount of heat you get by shaking the bag warms you up more than the little bag ever will.    The last football game I went to was 30 F so I took one of my body warmer along and it produced 5+ hours of heat!  If your looking for a better solution to help keep you warm during those freezing football games (or other cold outdoor activities) then this is the instructable for you. 

Uses I have found for the body warmer.
1.  Cold football games.
2.  Cold campouts.
3.  My wife takes them to bed with her.
4.  Long lasting localized heat for injuries or sore muscles
5.  Cold car rides to and from work
6. ect.

I have quite a few reasons for making this instructable (explained in later steps), but my main reason is I can't find any instructions anywhere else on how to make a sodium acetate hand warmer from beginning to end.  I want others to share my passion and help me come up with ways to make these body warmers better.   Ultimately I feel the best way to get more ideas flowing on the subject is to put an instructable together that described how to make a decent sodium acetate body warmer.

If you would rather watch how to make it than read it, then go to this youtube video.  (Note: I doesn't include instructions on how to make the insulated bag).
http://www.youtube.com/watch?v=SNF2DO6EXcw
 
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looop457 months ago
Wow it only gets that cold i Utah.
kbuechel9 months ago
Idk if this has been mentioned , I seen the comment regarding iv bags but what about new bladder bags ? like the kind that hook up to caths . I used to work in healthcare abit and can contest to the new ones being very strong . Don't know how expensive they are but I would assume they are readily available at any local medical store ... and thanks for the great write up :)
kevin_mic (author)  kbuechel9 months ago
I did some quick searching on bladder bags and cant find any very cheap. I did recently get some IV bags and am hoping to try them out. I am not sure how to get a metal disc through the small opening though.

If you try a bladder bag I would love to hear how it works out.
Help I can't get past the mushy stage. What am I doing wrong. I didn't do the carbon stage, do you think that is the reason?
kevin_mic (author)  nannysaunders011 year ago
I am not sure what you mean by mushy stage or carbon stage. Can you give me more details on what you are trying to do? Are you trying to make sodium acetate from scratch?
Just as a precaution can I warn anyone who is wondering whether to try a microwave to heat one of these - NOT TO TRY IT! All you get is an incredibly expensive Aurora Borealis effect in the cooker for about 10 seconds, then, that's it. No more cooker.
It's the metal clicker that has this effect, and boiling is so much safer and economical …
some microwaves can have metal in them. i can microwave things in a metal bowl with no problems.
One may have better microwave results by turning the power down. My family uses the adjustable level to allow thawing of semi-metallic cans, as well as better cooking for things such as broccoli. Thawing is usually just a level 2 or 3, plenty safe for juice concentrate. 4-6 will generally work for foods that like to sputter and pop, eliminating mess inside the cabinet.
I would warn to take breaks and knead the hot spots around.....easier to just boil.
lperkins2 years ago
If you want to get the mix more precise, use a thermometer as you're boiling it. The more concentrated the salt is, the higher the boiling point will be. My experimentation hasn't figured out the optimum yet, but if you have, you might take a reading and post it for reference.


What kind of sealers do you use to make the bags? I'm having trouble getting mine to not eventually come loose again.
kevin_mic (author)  lperkins2 years ago
I haven't used a thermometer, the thin layers of crystals on the surface is usually good enough for me. If you want exact results I think you would have better results using a hydrometer than a thermometer. I haven't tried either though.

As for the bags, I am using a heavy duty sealer that has a heat element both on top and bottom. Unfortunately even with this I have troubles like you have -- the seams blow out randomly.

I do have a different idea for making a bag that I have been meaning to post but haven't gotten the time. Basically you use your oven. First cut the vinyl for your bag. Second cut out a piece of thin fabric that is the same dimensions of the bag. With that fabric now cut 1/2 inch off all edges. Then place the fabric between the pieces of vinyl. This should make it so that the vinyl is touching the other piece of vinyl on all edges, but the center of the bag is vinyl fabric vinyl.

Now heat your oven to 350, place some aluminum foil on a cookie sheet and your bag on the foil. Then place it in the oven for 3 minutes (longer and the vinyl will begin to smoke). Pull it out. While still hot I have gone over the outside edges with a pizza cutter. Once cool, cut off a corner and remove the fabric. You will still have to use a different method to seal the final seam.

I have only created one bag this way, but so far the seams have held.
I have been wondering if a solvent-based vinyl glue would work well, but I haven't had time to find any.
acoleman32 years ago
now...will this get as hot as an mre heater? and if not....can you hack your idea to *get* it that hot?
kevin_mic (author)  acoleman32 years ago
No, it won't get as hot as that, and no you can't hack it to get it that hot. This isn't really a chemical reaction so much as a phase change reaction. You are getting heat when the chemical changes from liquid to solid. This change occurs around 150 F. So it really can't get any hotter than that.
bobtannica2 years ago
Very interesting instructable. Has anyone tried the IV bag route? How do you seal it?
heathbar642 years ago
this is cool! I mean hot!
I'll share what we use around the house. We make a cloth bag or use the sleeve off an old sweatshirt and fill it with about 4 pounds of popcorn. when you microwave this for about 3-5 minutes, it will warm your bed for several hours.
Hey Kevin...how cool...I have been playing with this technology all day yesterday at a Christmas Fair I was working at...in South Jordan at the equestrian center there...anyways...I came home and youtube searched to see if I could make it myself...(they were so expensive to buy) Saw your video..(realized you were a Utah brat too- Cougs! ) ....then I spent five hours trying to find pre-made metal clickers...thinking this would be awesome Christmas Gifts...(My family reunion is this Christmas and over 80 people will be there)....So I get the whole slap braclet deal...but I still would really like to buy a bunch premade...since I have to make almost one hundred for this party....and I am stoked that you said...you found them online for in mass quantities... do you remember where???...because I haven't seen any yet....Thanks!
What about a click style barrette? would those work?
kevin_mic (author)  SaratogaGirl2 years ago
I wish I could remember where I saw them. It was a couple years ago when I was searching for them and I only came across them once. It seems like it was on some Chinese website. I have searched since and never found them again. Sorry.
jsaunders52 years ago
Have you tried the "food saver bags"? They might work and if you have a food saver unit you can make the size you want and the unit will seal it too. They're made for the freezer.
I've been wondering how to do this for something like 20 years! Thanks for helping to satisfy my curiosity.

I have a simple idea for heating--so simple I thought someone would have mentioned it...but I haven't seen it here. My idea is to add some table salt to the water you boil it in to reactivate. This should have a lot of benefits/advantages:

 1. You've already chosen materials that are compatible with sodium acetate. Most likely, sodium chloride is also perfectly compatible with everything you're using.
 2. Salt is cheap and about as easily available as a material can get.
 3. Salt is easy to measure, so it'll be easy to do some trial and error and come up with the ideal ratio of salt to water.
 4. Salt dissolves easily in hot water.
 5. Salt is a good preservative. If the salt is concentrated enough, your boiling solution can be re-used many times without turning slimy or green.

All you have to do (if I'm right) is to keep using saltier water until the pack reactivates as fast as possible, stopping short of damaging your warmer. The water's boiling point is proportional to the salt concentration. When you find the right ratio, make a note of it, then make up a pot's worth of it. Find a jar or something to store it in between uses. When you're ready to reactivate, pour it back into your pot and boil as usual.

Remember that as the water boils, the salt will be left behind, so you will need to add more water to keep your salt concentration from creeping up. Maybe mark the inside of the pot you will use, then when you're done reactivating your hot pack, you can just refill the water to the pre-boiling level with cold tap water. Pour it back into your jar, close the lid and store it. 

What do you think?
kevin_mic (author)  sage instructor2 years ago
Interesting thought. I will have to give it a try and see how much it raises the boiling point.

I was also wondering what effect it would have in the solution. In water it lowers the freezing point, I wonder if it would have that effect in sodium acetate solution as well.
"I was also wondering what effect it would have in the solution. In water it lowers the freezing point, I wonder if it would have that effect in sodium acetate solution as well."

I was thinking about this. Adding salt to the SA solution itself would probably interfere with the crystallization process, preventing the packs from working at all. My reasoning is that the Na+ and Cl- ions would disrupt the structure of crystals as they try to form, keeping them from releasing any heat.
kevin_mic (author)  sage instructor2 years ago
I added sugar once to see if I could make the crystals softer in the bag when cool (like it is when it is hot). The solution still crystalized but it took a lot of heat out of the reaction. Ultimately it was still hard when cold. I don't know how salt would change things.
Well let me know when you find out!
Lose the salt ( and chose another team ).

This list of "advantages" & "disadvantages" doesn't make any sense.

You would have to add 58 grams of salt just to raise the boiling point of a liter of water by one half of a degre Celsius. But the boiling point of water is already 100C / 212F. This is 42C more than enough to melt the stuff.

Boiling will simply evaporate your water faster, not transfer heat to the bag faster. The needless use of salt will wear out your metal pans faster, and empty your wallet.

Water is cheap & plentiful, why on earth would try to keep the small amount of water you boiled vinyl bags of sodium acetate with? You definitely don't want any animals ( children ) or plants or yourself to have access to such dirty water.

Unless you live on a space station or the desert planet of Arakis, it is foolish to be that stingy with water.
You might need lots of salt to make a difference, but so what? That's the real reason to keep the salt water on hand--to save time and the right amount of salt, not to save water.

My suggestion was just for the purpose of quicker re-activation. Would it work? I don't know. Nothing wrong with a little trial and error, though. Practice makes perfect.
kevin_mic (author)  sage instructor2 years ago
I tried using salt the other night. The temp I was able to get for boiling water was around 204 F. With a bunch of salt I was able to get temps up to around 220F. Unfortunately a seam in my bag gave way. I don't know if it was a poor seal or the hotter temps of the salt water.

The main downside is it leaves a ton of salt residue on your bags and you have to wash them off.
Dr Qui2 years ago
Nice Ible.

I have purchased 6 of the 5" x 3" packs and 10 of the smaller rounds hand warmers of eBay. I use them for localized heat on my shoulder.

I may be able to help you with an answer re the clicker.  when I researched these before purchase I found an article that said the crystallization reaction that produces the heat is started in the tiny indentations that are on the disk.

The disks have been pressed to produce the cup shape that makes the thing click, but on closer examination there the lateral indentations on the disk are you can see that the disk is actually perforated along the indentation, these  perforations are almost invisible as they are press made. The reaction stats from this point, the reaction is started when the edges  of the  perforated slot snap past each other and this is where the seed crystal is formed that starts the chain reaction that makes the heat.

I think the disks are made from stainless steel.

All my packs need reactivated or i would post a close up of the clicker.

Rather than have a large vest type warmer that is difficult to reactivate, and also gives you that suicide bomber look  ( just one twitchy cop and it could be game over) Have you thought of making smaller warmers and sowing lots of  pockets onto a t-shirt or waistcoat ( this will give you the professional shop lifter look if worn without the warmers)

I have a fleece travel pillow that can store 4 of the 5"x 3"  packs i put the reactivated packs in while they are still hot and it acts like a hot water bottle for a few hours until they have cooled.  This is also useful if i wake in the middle of the night the pack is at hand and this saves me getting out of bed to fumble around trying to find a heat pack.

My view on reactivation is that i find that some of my commercially bought ones need to be boiled vigorously to get all the crystals to dissolve. 

.I intend to make some sore of basket that can be placed in a large pot so i can reactivate the packs on the wood stove in the shed and not waste gas I will post an Ible on whatever is come up with.

kevin_mic (author)  Dr Qui2 years ago
I have worried what Football security would say if they saw the warmers. So far when I need them I am so bundled in coats that it is easy to keep it in my coat, so they have never seen it.

As for smaller warmers vs larger ones, I have made both, I prefer the mid sized to larger ones. I like the vest idea. If you make one I would love to see it. I think it would be important to make sure the vest has insulation so that it only allows heat to escape toward the body.
fefrie2 years ago
You don't need to boil it to reactivate it. You could probably just let it simmer at 60-70c and will probably re melt just fine.
kevin_mic (author)  fefrie2 years ago
You are correct, boiling isn't required. But it is the fastest, safest way I know of to reactivate it.

Along those lines I have tried other methods of heating them up with varied success. Smaller ones can sometimes be successfully reactivated in the dishwasher. I have also used a crockpot to reactivate them (takes forever but it works).

The problem is that I want faster warm up times and safer methods. Even boiling has its problems. My dad ruined a few of his hand warmers because he forgot about them and boiled all the water out. Fortunately he didn't start a fire.

It seems to me the best way to reactivate the sodium acetate would be to heat it directly. Some sort of heating element in the bag itself that will only heat up to 140-150 F (60-65 C).
When I said boil, I just meant that the water didn't have to be at 100c to get the SA to absorb the heat.

The difference between the melting point and water simmering at 70c or boiling at 100c isn't enough to make a difference in infusing energy into the SA.

If you want to put more energy into the pack, then I would suggest using a pressure cooker so that the water temp can go above 100c, but the danger involved would not be worth it.

Puting metal in the bag is a waste of time if all you want is for it to heat up to 60c. Water can be kept at that temp more easily than hotspots created by a heating element.

Simplest thing to do is when you're done with them, take them home and put them in the crockpot. Probably the most energy efficent method and kindest to the vinyl or plastic bag.
kevin_mic (author)  fefrie2 years ago
I tried both temps to see the difference. Heating a bag on simmer (keeping it around 164 F) it took between 25-30 min. Heating a similar sized bag (slightly larger) with boiling water it took under 15 minutes. So the difference between simmer and boil is about half the time to reactivate.
I bought an 'acetate-style' warmer from a local pharmacy, which later got bought-out by CVS pharmacies. The unit is called the RE HEATER and is made (appropriately enough) by Re-Heater Inc. - a USA company, out of Gardena California. The instructions give a hint at the limitations of the technology. When you 'boil' the pad, you are to keep it off the bottom of the pan with an overturned small saucer, or the like. The bag is heavy, textured vinyl, like an air mattress or beach floatation toy. Vinyl, like all plastics hava a plasticiser agent to keep them pliable. If you heat this thing up dry, the plasticiser will evaporate out more readily than if it is submerged in water, where you have a more uniform heating of the whole surface area. The principle of the clicker is due to mechanical hysteresis. It's kind of like when you were a kid playing with the older snap-action light switch, slowly pushing it in one direction, then releasing it, then back a little more, until, SNAP!, it flips direction and stays in it's new stable state. (then of course Dad yells at you to quit playing with the light switch - but then, I digress). Kept too long in storage, the acetate crystals may grow on their own, making it necessary to reheat the bag before use. Once the crystals form the solution isn't hyper saturated, but stable, and you can't get it to warm.
I think the bags that hold the IV solution in hospitals would be great. they are very puncture resistant and dont harden in low temps.
kevin_mic (author)  bhaberman-browns2 years ago
Any idea where someone could get an iv bag, and how much they cost?
http://www.dealmed.com/Empty-IV-Container-Bag-1000ml?utm_medium=CompCPC&utm_source=nextag&utm_campaign=CSS&gdftrk=gdfV21435_a_7c1031_a_7c4310_a_7c85605

I just did a quick search on DuckDuckGo.com for "Empty IV bag"
I was thinking the same thing (about hospital IV bags). There are a variety of different ones. You definitely wouldn't want to just grab any IV bag, but if a relative or someone you know is in the hospital you could ask for the empty bag. When my wife gave birth I asked for the IV bag (for a different project) and she gave them to me. They were just saline bags though...
Heh. Zoobie warmers. Great instructable :)
Dr Qui2 years ago
Could you use an old busted steel tape measure to make the clicker?
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