While doing my research and today purchasing an Optimus Vega, I came across a number of videos on refilling/combining isobutane canisters. For $20 you can purchase a kit that appears to have several adapters. One allows you to transfer gas from one isobutane canister to another to combine two partial canisters into one or refill a small canister from a large canister. This would eliminate having to carry a partial canister just to use it up and allow you to buy the much more economical large canisters. There is also an adapter to fill the isobutane canister with straight butane that comes in a container similar to a spray paint can, and a third adaptor to run a canister stove using a 1 lb propane canister.

Obviously use a good scale when performing this procedure.

A few questions: Does anyone use such an adaptor? Can you run an isobutane stove on straight butane or straight propane, and if so, do the characteristics of the burn change with the fuel?

I saw it somewhere, but the mix for isobutane is I think 20% propane and 80% butane? I am thinking that using a scale and the two adapters that you could refill and match this mix.

Fuel Canister Refill Adapter

Butane vs Propane vs IsoButane

It's been discussed here quite a bit. My personal takeaway: not worth it.

I use the exact one that you reference from Amazon. I purchase the large, 16oz isobutane canisters and refill the smaller ones as needed. It saves a few bucks, but for me as important is knowing I am leaving with a full canister and not needing to bring a second one "just in case". I also don't like the waste of throwing canisters out, so this lets me reuse them.

I bought one of these tools two seasons ago, and I use it routinely. I bought a big canister to fill smaller ones, like above, and I find it useful to consolidate half-used containers. When the canister is empty, I use the little JetBoil branded key to puncture it and take it to the county for recycling.

Schweady, curious why you don’t really care for it? Just didn’t find it useful? I could see that, especially if a person uses up their fuel canisters. I always come home with half-used containers.

Just remember: PV = nRT, and it will work a lot more effectively for you!

jillpine: "I find it useful to consolidate half-used containers. When the canister is empty, I use the little JetBoil branded key to puncture it and take it to the county for recycling. "

This is what I bought one for. It's much nicer to have 2 "full" ones than six partials. There is plenty of information out there on the process of doing it - does require attention to detail.

I have the G-Works gas saver to transfer between partially used canisters.

I found this blog post by Hikin' Jim on Adventures in Stoving to be really helpful about explaining the process and how to do it safely.

There are three different chemicals used in “isobutane” canisters. They are:
Propane
Isobutane (chemists call it 2-methylpropane)
Butane (also called normal butane or n-butane)

Propane has the lowest boiling point and highest vapor pressure.
Isobutane has a higher boiling point and lower vapor pressure
Butane has the highest boiling point and lowest vapor pressure.

It would NOT be safe to fill an “isobutane canister” to its completely full weight with propane. The pressure would get too high and the canister could explode. Those green bottles of propane have those heavy walls for a reason, the pressure in there is high when it is full.

Most high quality canisters are filled with roughly 80% isobutane and 20% propane. The isobutane normally has a bit of n-butane contaminating it. This mixture produces enough pressure in the canister to keep your stove working in three season weather. You’ll probably have too low a pressure in winter for the stove to work well. (A remote canister stove in which the canister can be inverted helps with this problem.)

It is cheaper to use n-butane in this mix rather than isobutane. However, since n-butane has the highest boiling point and lowest vapor pressure of the three, this compromises the ability of the stove to work well at low temperatures. Coleman uses butane in their mix. Useful in summer only imo.

So, don’t fill these canisters with just propane.
Butane (n-butane) is okay but only for warm weather.
Finally, as you mentioned, use a scale and don’t overfill the canister.

To the op, I missed the full question about putting a different fuel into an isobutane can. I use the transfer tool but not in that manner, and I wouldn’t put a different fuel in a container not labeled for that fuel. I apologize for any confusion in my response. I was addressing the transfer tool, not the full question about propane or mix-your-own.

LarryS48: "Most high quality canisters are filled with roughly 80% isobutane and 20% propane. "

Thank you for this correct ratio. I corrected it in the OP.