At Walgreen’s Drug Store they were having a 1/2 a BOGO (Buy One Get One) where you have a BIG sign saying “50% OFF” and then little tiny type saying “on the 2nd one when you buy one full price”, on Ethanol Rubbing Alcohol.
$2 for a US pint. 16 ounces. About 473 ml. I bought two, then tested it in the Trangia alcohol stove.
Testing 70% Ethanol / 30% Water Mix
I put my usual coffee / tea unit of water (400 ml / 15 oz eyeballed) in the regular tea kettle (about an 8 inch base) and put it on the stove.
It took 5 minutes to “bloom”. Until that time it burns with a small soft blue flame, then it spreads out to the burner holes. Initially there was some flame from the burner holes, but I think that was some alcohol spilled on the top in the filling. It was filled to about 1/4 inch from the very rim.
At the 10 minutes mark, we got the first simmer with 400 ml
12 minutes to whistle stage, then I poured that over tea bags and put in a measured refill with 500 ml cold water.
8 minutes it was back to the the simmer and at 11 minutes to whistle
So this is now about the 23 minute mark. From this point forward I’d just dump the boiling water and do a fast faucet refill to “about the same weight” and back on the stove.
Every roughly 8 to 10 minutes, I’d repeat. At the 50 minute mark was the last full whistle (pot number 5 ) and at that point the flames reduced to roughly strait up from the burner holes / outer ring area. And another pot fill.
At the one hour mark, it was definitely at the simmer / low boil, with a good plume of steam out of the spout, but not enough to whistle. I left that water in for the rest of the test. The flame, at that point, was starting to curve inward and about the width of the main fuel central are.
It continued in that “steaming and simmering” mode to about the 1:10 minute mark with ever decreasing vigor. At 1:07 it had started to “flicker” a bit. At the 1 hour 10 minute mark, it gave a very soft pfit sound and was out, the last simmering sounds ended. Looking inside the stove, there were 2 small drops on the very bottom, each about 1/2 the size of a paper match head. Clearly almost all of the water ends up evaporated and passes through the fire.
Evaluating The Test
So, filled to about 1/4 inch from the top with 70% ethanol 30% water, the stove is still competent, and is VERY well behaved. Not even a “2nd Bloom” increase of power level. This fuel makes a soft blue flame, yellow tips when the pot is removed from the burner, but all blue when in use. It is a bit slow to start, taking a full 5 minutes to bloom; and with no “2nd bloom” to a higher power mode. Still, it will bring 500 ml of water, cold from the tap, to a full forceful boil in 10 minutes or less, once the stove is running full power. You get 6 rounds of this from one fill.
I think this sets the upper bound for “water in fuel” at 30%. More water than that will burn poorer, take a very long time to “bloom” to full power, and likely start to leave a water fraction as fractional distillation becomes a problem during use.
The second implication being that to tame the Kleen Strip “Fuel Denatured Alcohol” 50:50 ethanol / methanol + denaturant mix (that caused a runaway heating problem / spitting earlier used on a cork pad): adding just 15% of the total fuel volume as water would make the ethanol component about right. Personally, I think 80% or 90% ethanol, or 20% 10% water in the ethanol fraction, would be better (call it 160 to 180 proof) so would likely keep any water added to the “Fuel Denatured Alcohol” mixed fuel down in the 5% to 10% of total fuel level to start with. The MSDS for this particular Kleen Strip “Fuel Denatured Alcohol” blend does not list gasoline as part of the denaturant mix.
Lists Ethanol at 30% – 50% and Methanol at 40% – 60% and lists specifics as trade secret. The Kleen Strip can itself lists them too, but also says under “Warning:” that it has some “methyl isobutyl ketone” which I presume is the denaturant compound. I suspect it will also be rather flammable while lowering vapour pressure and is part of the “enthusiasm” of the fuel in this stove; but that requires more investigation than I’m willing to put in at this time.
For those “Denatured Stove Fuel” blends that DO have a few percent gasoline / benzine type compounds, the water would likely cause a phase separation and you can remove that unwanted component… leaving just the things like methanol, ethanol, acetone and other ketones that are water soluble.
I’m of the opinion that a simple measure to control the spit and fire issue on the Kleen Strip “Fuel Denatured Alcohol” would just be a small addition of water, about 10% of total fuel volume. Similarly, mixing the Kleen Strip “Fuel Denatured Alcohol” about 1/2 and 1/2 with this Walgreen’s Ethanol/water mix “Rubbing Alcohol” will likely improve both of them. Making the Kleen Strip “Fuel Denatured Alcohol” safer with lower runaway potential, and increasing the burn energy of the water diluted Walgreen’s Ethanol Rubbing Alcohol.
I got this Rubbing Ethanol at Walgreen’s. Other pharmacies may also have it, though I didn’t see any in a quick look at CVS or Walmart. It was $2 / bottle for a pint ( 16 ounces ). This is cheaper than HEET brand Methanol at the Auto Parts store. (About $3 for 12 ounces or $32 per gallon). That’s $16 gallon for the Walgreen’s Ethanol ( $2 x 8 pints in a US Gallon) stuff, about double that for HEET methanol. The Kleen Strip “Fuel Denatured Alcohol” was a bit over $5 for a quart ( 32 ounces ) or $20 / gallon, so more or less competitive especially when you allow for the greater fuel value. (Dividing $16 / gallon by 0.7 to get the fuel fraction only, gives $22.86 / gallon of actual ethanol for the Walgreen’s Rubbing Ethanol) It still ought to be 1/2 that price / gallon for straight methanol, by the gallon in hardware stores, outside of California (AND being the fuel the stove was designed for, no “tuning” of the fuel required…)
Overall, I like the idea I can have a “Turbo” option using the “Fuel Denatured Alcohol” straight from the can, but knowing that I need to take some care about thermal runaway at the 8 to 10 minute mark (after making both the coffee and the noodle cup…) or I can use “Ethanol Rubbing Alcohol” for a well mannered stove that will run an hour without any issues at all. Even if a bit slowly. Or any points in between via mixing. I suspect that in very cold weather, or windy conditions, the Kleen Strip “Fuel Denatured Alcohol” would do better straight, and the “Ethanol Rubbing Alcohol 70%) would struggle to “bloom”. The flame is weak and sensitive to drafts during the early pre-bloom warming process. At some degree of cold, the heat loss will exceed the production of the small weak flame and the stove will not reach operating temperatures / power output. Similarly, on a hot summer desert trip where thermal runaway would be more likely, the 70% Ethanol rubbing alcohol would bloom quickly and be safer. The good thing is that both those extremes are outside of my tolerance for “fun camping experience” ;-)
I’m also now quite certain that the “runaway stove” issue was just a result of not feeding the stove the design point fuel of Pure Methanol. Now if someone can just convince the California EPA that banning the proper fuel from the hardware store is going to create a LOT more camping fires, potentially forest fires, and a LOT more pollution in the end, along with burnt people, tents, critters and more…
@EM: I looked up the product by the NDC number printer on the upper-right side of the lable, and then to the product page at
Where it is described as “70% Ethyl Rubbing Alcohol”
And these inactive ingredients: acetone, denatonium benzoate, methyl isobutyl ketone, water
Nothing there about any other kind of alcohol. The denatonium benzoate is mondo bitter, and is present to strongly dissuade swallowing. One of its first uses was as an additive to methyl (wood) alcohol, also to dissuade consumption of this poisonous alcohol. It is also now used in Oregon in Anti-freeze.
@EM: correction… the NDC number is printed on the bottle, not the label.
Yes, the rubbing alcohol is just Ethanol. It is the Kleen Strip can of Denatured Stove Fuel that is 1/2 methanol and half ethanol.
I’ve re-written some of the article to make it clearer just when I’m talking about Walgreen’s Ethanol 70% Rubbing Alcohol and when I’m talking about Kleen Strip “Fuel Denatured Alcohol” blend of 50:50 Ethanol / Methanol.
It’s wordier, but depends less on pronouns and already knowing the historical context of the Trangia having a thermal runaway in warm use on a cork pad for an extended period.
I’ve also run a “test” on the 70% Ethanol with about 1/4 of Stove Fuel added, in that I topped up the Ethanol 70% bottle with some of the Stove Fuel and then made morning coffee with it. Worked very nicely.
@EM: hmmm. Blended 70% Ethanol and Stove Fuel! Perhaps call it ‘Stoveanol’ :-)
Q: After combining, do the liquids mix, or separate? Since water and alcohol are miscible, I’d expect those 2 to stay together. Wondering about whether tou get layers, or a shake-induced imulsion, or some other distribution of the fluids.
The “Stovenol” :-) mix is 100% blended and water clear.
After about 1/2 a fill burned, stove cooled, then re-lit this morning, it was hard to light with the striker. (A disposable BBQ lighter out of butane but still has working piezo bits). It lit fine with a match but was slow to “bloom”. This leads me to think some fracional evaporation takes place with an alcohol rich first burn concentrating water in the residual fuel.
Burned from full to empty left little behind, but the stove is running very hot then. It is possible that repeated short burns with cooling between might result in very dilute fuel near the end. Then again, by definition that means you did burn most of the actual fuel components. So a dump and refill would not be wasting much at all. More just a caution to carry matches along with a sparker when using water diluted fuel.
I used the little crossed titanium pot support this morning to make espresso in the Italian one serving pot. Worked well, but the heat dampening of the metal in the flame was more noticeable with the dilute fuel. Letting it warm up before setting a big chunk of cold aluminum espresso maker on top was a good step.
I’ve decided to keep the pie tin in the kit and not use aluminum foil, despite the couple of grams more weight. Why is pretty simple. The Trangia pot holder gets hot. This makes what it sits on hot (like counter tops or grass… ) With the pie tin upside down, stove on top, it insulates the stove from the ground, grass, tent, counter, whatever. Good for any weight up to 1/2 kg water in a kettle so far, but I’d not put a cast iron skillet on it ;-) Even upside down it ought to catch any spatter, but the added heat removal looks to prevent thermal runaway anyway in the first place.
So it both keeps the stove at a nice “warm but not too hot” operating temperature that avoids thermal runaway, and conducts the excess heat to the air keeping the surface under it cooler. Then also covers the 7 inch spatter area (in the event of a thermal runaway burp) with a metal barrier, and the rolled under rim prevents any small liquid bits from running off. Since only a small bit was burped out in the runaway event, I think this is likely enough catch basin. Especially given that it prevents the heating in the first place. I’m using a Marie Callender’s steel pie tin, not a thin aluminum job.
So overall, I’m quite happy with the stove and available fuels, I’m happy I got to learn how the different fuels and heat removal (or insulation) affected the stove before being 20 miles from nowhere in a tent, and I really like the added flexibility of the titanium pot support and pie tin.
@EM: Seems to me that the burnable fuels evap at a lower temp than water boils, so you have a bit of a ‘distillery’ effect during operation, generating accellerated amounts of burnables when hot, but also unpressurized steam, at a lower temp than the alcohols. This likely puts a limit on the heating of the liquid, perhaps preventing the 2nd bloom.
On the topic of the ‘2nd morning relight’, several thoughts: 1) a smallpiece of calcium carbide in the fuel prior to re-light, producing acetylene, might act as the accellerant you need to enable the re-start by spark. Or, 2) separately light a small amount of full-strength fuel mix, and ladle it into the diluted fuel. Or, 3) put 1 small capfull of bacardi 151 rum in your ladle. They don’t call it ‘fire water’ for nothing :-)
I’d not want to put Calcium Carbide in the stove. The left over goop would tend to clog the wick in the walls and / or the burner holes. And it’s easier to carry a bit of higher concentration fuel (see below).
has a nice graph in it for iso-propanol / water:
So you can see that there’s an equilibrium point where an azeotrope forms. With excess of propanol in the vapor phase on one side and water vapor on the other. From that article:
However, if you raise the temperature above that point, you can drive off a non-azeotrope ratio (limit case: at 212 F / 100 C the water alone would boil, and ethanol even easier, so everything would boil out).
What make this even more complicated is that the liquid between the walls of the stove can be at a different temperature than that in the middle as the walls get hotter at the top and the wick will tend to raise the liquid into that zone and evaporate all of it. Once the stove has bloomed…
FWIW, today I bought a pint bottle of 91% Isopropanol at the drug store ( way over priced at Rite-Aid at $2.85 ) and just added about 15 ml to the stove when it would not spark light. Liit fine then.
This was maybe a 2/3 “used mixed fuel / water” an 1/3 the new stronger fuel. It burns with a very nice blue flame unless you lift the pot, then the flame gets yellow tips. I saw no soot form. As this is now a mix of 4 liquids (methanol, ethanol, isopropanol, water) the azeotrope graph would be very complex and will change as components / ratios change.
But all I care about is that I can use up this bottle of mixed wet fuel as I like it. Either using a match to light it when “weak”, tipple in more from my fuel bottle, or just top it up with a bit over very fuel rich 01% iso-propanol.
I suppose if I really cared I could work out just what mix of which stuff into the 70% ethanol fuel made it stable against short runs, but I don’t care enough. I’m happy that I can use the “Fuel Denatured Alcohol” with a 5% to 10% water added in safety and without re-light issues, and that I can get straight methanol as HEET that works fine as is, and will leave the 70% Ethanol as a backup fuel option, knowing I might need to add a bit of HEET or 91% iso-propanol to the dregs in the stove for an added cold start. So far I’ve not needed to pitch out any spent leftovers…
So IF I ever have to buy 70% ethanol fuel at a drug store, I’ll just add a bottle of 91% iso-propanol too and use it as top-up on semi-spent stove contents. It, btw, can be run “straight”, but tends to soot the bottoms of pots somewhat. Similarly acetone. I suppose I could also just add a bit of acetone to any leftover fuel dregs.
Or I can just plan my cooking such that the fuel loaded is about what is needed for the particular dish and let it run dry, or nearly dry. Then the next fuel load resets the mix to good / starting and off you go again. A lot of the “soda can stoves” need measured fuel loads as they have no snuffer to put them out, so it’s a common mod of operation. 1 tsp is the standard load for a cup of coffee, IIRC.
With so many ways to deal with it, I’m not really worried. Just need to know that behaviour can exist and what the coping options are. So if you have a lot of fuel, and not matches, you might choose to just dump the dregs. If short of fuel, but have a bit of acetone or iso-propanol, tipple a bit in. Or if you are about to do a long simmer on a slow cooked dish, add some regular fuel, light it, put the control ring on, and run it to dry…
This guide gives a good intro to ethanol distillation and has the distillation graph for ethanol / water mix in it:
Click to access distillation.pdf
The basic bit being that ethanol will be concentrated in the vapour at any point below 194.4 proof or about 90% mole. So as the stove operates it WILL preferentially leave water behind in the bowl of the burner.
As I’m running a mixed fuel with methanol in it (from the “Fuel Denatured Alcohol”) we have a three liquid azeotrope problem and I have no idea how that’s going to work out other than that methanol comes off early in making moonshine… but does it bring much water with it?
Given that the iso-propanol curve has a crossover to excess water in the vapor, my guess is that methanol is like ethanol only maybe even an earlier vapor exit.
Thus the added iso-propanol doing a better job of “fixing” the mix as it takes more water with it when it evaporates.
But that’s just a guess unless / until someone actually finds a 4 liquid graph ;-)
Me? I’m just going to pour a bit of iso-propanol in when I need it to light, or get a match. And if the match won’t light it, toss out the 1/2 ounce of water in the mostly empty stove and just refill it. It’s easier ;-)
Here in Central Florida we have Rexall.com-branded (and DolgenCorp-LLC distributed) “active ingredient isopropyl alcohol 91%” available at Dollar General stores for $3/quart (thus a much more appealing $12/gallon). So I don’t bother with drug-store chains, e.g., Walgreens, which no longer seems to sell rubbing alcohol at strength >70%, but maybe my sample-size is too small, or their inventory management is poor.
Label claims only (i.e., 1) “inactive ingredient water“. “Other information • does not contain, nor is intended to act as a substitute for grain or ethyl alcohol • will produce serious gastric disturbances if taken internally”. Sure beats a warning like we’ve been told to expect for methanol, e.g., ‘will destroy liver or kidneys if ever absorbed through skin’.
To keep the record straight, the warning I saw about methanol here on “Musings from the Chiefio” was actually quite different:
gallopingcamel says: 17 December 2019 at 5:37 am
[….] Methanol is toxic given that it is converted to formic acid in the body which destroys the optic nerve. Thus consumption of tiny amounts of methanol (~10 ml) causes irreversible blindness and larger quantities will kill you by destroying vital organs. What is less well known is that you don’t have to drink methanol to suffer irreversible health issues. Methanol is readily absorbed through the skin.
That 10 ml. is only 2 teaspoons on this side of the Pond! Yikes!
In the UK military we take the brewing of tea very seriously. We want our tea breaks but we need to do it fast! In my tank regiment we had electric kettles inside our vehicles but seldom used them as they were slow.
Our preferred water heater was called a “Benghazi”. This consisted of a cylinder standing on three short legs welded at the bottom to a truncated cone so as to form a chimney about 30 inches tall. The space between the cylinder and the cone contained about one gallon of water.
The Benghazi was powered by a 4 ounce can of gasoline placed between the legs supporting the body of the device. Once ignited the device created a powerful updraft and an impressive roaring sound. The water boiled in ~45 seconds.
Hi, “Compu Gator”.
My staff used to laugh at me for getting their retinas photographed (we were building lasers that produced Giga-Watt pulses).
They laughed at me for requiring them to use gloves when handling organic chemicals such as methanol and dyes.
One of the dyes we were using was Rhodamine 6G used in lipstick back in the 1970s. I got the last laugh when this compound was declared a dangerous carcinogen.
Our lasers produced blue light based on the fluorescent properties of a coumadin salt that is the active ingredient of many rat poisons. This toxin can be absorbed through the skin, especially when dissolved in methanol.
Walmart sells rubbing alcohol in two strengths (67% and 91%).
I recommend the 91% product for cleaning fiber optic connectors because it evaporates quickly owing to the low water content.
Don’t drink it! While it is much less toxic than methanol it will give you a hang over that you will never forget!
My chemistry professor at Cambridge university was Dr. Saunders, a dapper gentleman who lectured us in a three piece suit. During WW2 he weaponized Botulinus Toxin and tested it on himself. His most toxic compound has an LD50 (half of those exposed will die) of 13 ng per kilo of body mass (inhalation) .
What this means is that 1.3 micro-grams can kill someone who weighs 100 kilograms. Thus 1.3 grams is enough to kill one million people.
Dapper though he was, Dr. Saunders got our attention.
The most toxic chemical I have ever worked with were the crown ethers. I don’t remember the LD50s, but they were chelators and iontophores that made cell membranes leaky.
Crown ether? That’s a new one for me. Interesting wiki…
Were I working with methanol all day, I’d do the gloves thing, but pouring an ounce in a stove, there just isn’t enough mass contact, even if some splatters on you. It almost entirely runs off and evaporates. You would need to absorb about 1/4 to 1/3 of the loaded fuel…
Per the “Bengazi”: now that’s my kind of kettle!
@EM: As I read the “Bengazi” description, it seemed to me a customized Shell from an expended tank round. Fire once at 4:00 pm for tea time…