I did some research about isopropyl alcohol, turns out that it contains 14,000+ BTUs per pound - a lot better than denatured, ethyl or methyl alcohol. So the trick is to find the purest.

I went to Wal-Mart and found Iso-Heet and 91% isopropyl medical alcohol. Since the Iso-Heet didn’t list purity, I did a side by side test using two identical Ion stoves, Iso-Heet in one and medical alcohol in the other. The Iso-Heet flame was twice as tall. I switched stoves as verification and again the Iso-Heet stove produced the greater flame. I have e-mailed the manufacturer asking for the concentration.

Initial test has not been conducted with thermocouple, but observations:

1. The flame is VERY large and hot, especially compared to a denatured alcohol burn of the same volume in the same stove. Where the denatured would maintain a low blue flame, the isopropyl alcohol makes a large yellow flame over the top of the windscreen, very similar to what my original Cat Stove would do.

2. The pot was filled with one pint of water. Time was not kept, but the pot developed bubbles quickly. A roiling boil was achieved with fuel still left to burn. Amount of fuel used was 12 ml.

3. The soot left on the pot was a lot more than is normally experienced with denatured, ethyl, or methyl alcohol. This observation has been relayed to me on multiple occasions by people that have used Iso-Heet when normal Heet was not available. It is one of the reasons I have not tried isopropyl alcohol until now.

4. The smell is different with isopropyl alcohol than with denatured or methyl alcohol. I don’t know what this really means.

5. On the bottle, there is not the product warnings of death and blindness associated with methyl alcohol. I assume that since isopropyl is used in medical applications, that it us safer for handling.

Conclusions:

1. Continued testing for efficiency is definitely worthwhile.

2. Soot may be only a cosmetic problem, easy to fix by rubbing the soot off. But there may be a way to control the soot. Since this would be considered a “rich” mixture, maybe more air to fuel ratio is needed. This will take some research in how to apply it to a homemade stove.

3. More data needs to be collected about specific gravity, vaporization point, and boil point of isopropyl alcohol.

Any chemists out there or anyone with some experience that can help me out?

you're right on having too rich a mixture. The reason for all the soot is because of the extra carbon atoms in isopropanol that when the iso is not burnt completly collect on the pot. The vaporization point as well as the boiling point of iso would be about the same as ethanol or methanol I would think, but the vaporization point would determine cold weather performance.

Can you widen the slits that allow air in? I haven't made one yet so I am assumeing how the soda can stove works. On an auto site I read a lengthy article that mathmatically showed how fuel (petrol) burns more efficiently the colder the ambient air temperature. However- the temperature of the metal that is metering out your fuel will contract in extreme cold, maybe less so in an alluminum can, but it may cause more fuel to come through... then again the air slits should contract the same negating the problem.

Some fuels also give off carbon as a natural biproduct regardless of the air/fuel ratio. I took Chemistry 151 for scientists & engineers at UMass, but I forget if this is the case with isopropanol.

I hate soot though. Gets all over everything. We use pure isopropanol where I work for disinfecting tabletop surfaces & equipment before testing water for fecal-coliform. It smells kinda nasty when it burns (not sure if this would affect taste of food). Funny thing is, I don't notice soot on anything. Ill have to do some experiments with it tonight. Maybe I'm wrong...

Until then, it's either ethyl or methyl :)

Did the test last night with "Pure" Isopropanol. Still got some soot. I think elemental carbon is a byproduct of burning isopropanol, regardless of the A/F ratio. It also smells like crap.

Methanol for me :D!

thats pretty interesting. the stuff over here in london has a mega mega BRIGHT deep purple colouring (the stuff i used to get in australia was mostly clear with a light purple metalic glint to it). (reeks when burnt. leaves lovely sooty pot and wire mesh ring on my brasslite).

have long since turfed the bottle so dont know its exact concentrations.

i am making a pot cozy today, so will be testing on the weekend.. i have about 2 shots of famous grouse left, which is 40% vol, so i will see how well a nice blended scotch whisky burns ;) heheheh

i do have some medical alchohol here somewhere... i will try and find out its mix/concentrate....

dont know if its possible to get pure isopropanol here in london...

Two reasons for soot: 1. isopropanol has more carbon than methanol/ethanol
2. It creates a rich mix when burnt in a stove meant for ethanol