Originally Posted by
Lasse
According to the vapour pressure data I mentioned, there won't be any butane hissing out from your butane canister at 0°C (freezing) since all your butane will be in liquid form. You would need a pressure below atmospheric pressure inside the canister to volatilize the butane at 0°C. So pure butane would not work at all in a gas stove at said temperature. Of course, you could just strap you canister on your belly underneath your jacket to heat it up during the day as you would do with a small flask of alcohol at really low temperatures to make ignition easier (note the difference between making it easier and making it possible).
Luckily, for gas stove users, you can also buy gas canisters that don't contain only pure butane, e.g. mixed with propane which has a much higher vapour pressure (starts to become vapour at -42°C).
On one of my last winter camping trips, my alcohol stove worked without problems at -10°C, starting the fire was just a bit slower than usual (cheap lighter) but everything worked fine. There might be a reason why alcohol stoves are very popular in Scandinavia, including in military use...
Conclusion: if you choose the right gas canister (not the pure butane one) you'll be fine below 0°C, just like you would be fine with alcohol.
"Butane" is short hand for a mixture of gases that are commonly used for backpacking stoves. The real mixture is a mixture of propane, butane and isobutane (which is really 2-methylpropane). I doubt that you can find pure butane for any stove because pure butane has a higher boiling point than the other gases. Once you add the gases together you can push the useful temperature down but not by too much.
If I were to do winter camping...not likely and really not all that germane to the thread...I'd use white gas (also known as naptha) rather than alcohol.