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…