[Bachmannn]

Hi:

I am looking for assistance with the formulation of the camping hand warmers that basically use
the exothermic oxidation of iron. I know sodium chloride (I think) is usually used to increase the rate of the reaction. Some other ingredients are used to hold the heat, etc.

I would like to improve on this process. Can someone point me to a source for more information or even an individual?

I'm a  budding entrepreneur and could possibly pay a consultant for some help as well.

Thanks

Alex

[kevin_chuca]

Hi,

I've found de components, but I am looking for the proportions and best way to mix them to optimize the reaction: iron powder, vermiculite (or sand), salt (sodium chloride) and water.

Two useful links:
http://www.theheatcompany.at/e-funktion-waermekissen.html
http://matse1.mse.uiuc.edu/metals/k.html

Please, let me know if you find further details

All the best,

     Claudio

[Bachmannn]

HI :

I've seen these websites and am familiar with the basic concept.
I've even bought some Iron and experimented mixing it with salt and water.
But not much heat.
Maybe the Charcoal and Vermucilite are very important. I thought they only help the heat
stay around longer but the actual heat is generated by the Iron, Salt and Air/water.

Maybe more experimenting is called for

Alex

[Arkcon]

Surface area, and volume of the inert material, and the thermal mass that provides are also likely contributing.  If you're experimenting, how much heat does the commercial pack really generate?  Rip one open, put in a coffee cup, and measure it with a thermometer.  What does your mix do?  Is it 85-95 % what the commercial mix does?  Maybe that's the best you can homebrew.