Moulder Strip Directions

[ncwild]

Cannot find specific directions on how to build this “Moulder Strip”.  Have seen numerous references to this, and links.  Can anyone advise on materials and building this?  Thanks.

[Bob Moulder]

Hi Tim,

Not a whole bunch of directions needed because it is pretty simple!

The only critical element is the copper strip, which should be 1″ wide with a thickness of 20-25mil, which is .020″ to .025″.

The strip needs to be long enough that one end sticks well into the flame at the burner head, and the other end has good contact with the canister. The end at the canister should be formed a bit to match the canister radius, but I have found this not to be super critical.

I attach mine to the canister with a nylon Velcro cinch strap that holds the strip to the can very firmly. I also use a thin piece of silicone sheet as an insulator.

For the basic setup, that’s it!

In really cold weather — and especially with the larger 220g canisters — it helps to also add a canister cozy. This can be made of 1/4-3/8″ closed cell foam or 2-3mm neoprene. Both work perfectly.

 

 

 

 

[ncwild]

Thanks Bob.  I assume you only put insulator only on the outside, velcro side, of the copper?

” thin piece of silicone sheet as an insulator”

[Bob Moulder]

That is correct, Tim.

[ncwild]

Do you think this would meet the specs?

Link:

 

[JCH]

This seems better aligned with Bob’s suggested dimensions…more material than you need for one strip tho.

[Bob Moulder]

Tim, I suppose you could hammer those out to the correct thickness and width, but the stuff in JCH’s link is perfect.

In some of the threads (sorry I’ve lost track of exactly where!) some people reported getting some copper roof flashing (or some such) cheaply and in small quantities at Lowe’s or Home Depot… or perhaps elsewhere.

I was doing so much testing that I bought a 20-foot roll at Basic Copper. I’ve given away so much of it that I have very little left, or else I’d just send you some!

[Jerry Adams]

my article https://backpackinglight.com/evaporative-heat-loss-in-upright-canister-stoves

especially look at people’s comments

and threads https://backpackinglight.com/forums/topic/98947/ and https://backpackinglight.com/forums/topic/calling-all-fuel-canister-engineers/

I never got the Moulder strip to work very good, because I used the Soto Windmaster, because it’s taller, so the strip is about 1 inch longer which makes a big difference.  Shorter stove works better., that is, the distance from the top of the canister to the top of the burner or where the flame comes out where you can put the strip

[Bob Moulder]

Jerry, as I recall you never used copper for the strip, only aluminum.

I know all the material properties charts suggest that this or that amount of aluminum should, in theory, work; it doesn’t.

If you try copper exactly per spec you will see how well it works, down to -21°F anyway.   ;^)

No offense, but the photo below is nowhere near spec — no surprise it doesn’t work!

[JCH]

I have found it best to always listen closely to the man for whom the device/technique is named :)

[Jerry Adams]

You can use aluminum, but it doesn’t conduct heat as well so you need a thicker piece

What was concluded in one of those threads was that my problem was the stove is taller, so the strip is longer so it takes longer for the heat to get down to the canister.

Look at your stove in your picture, and my stove in your second picture, my stove is way taller.  1 inch or so is what I measured.

This is one of those topics where the combatants could easily get into an argument about whatever, but we have been fairly well behaved : )

By the way, an aluminum foil reflector weighs a lot less and there’s no time delay for the heat to get down the strip.  Gary graciously tested it and he had a positive experience but still prefers the strip.  David tested it but it didn’t work so good, I think he didn’t shape the foil reflector properly so it didn’t reflect down to the bottom of the canister.  I think maybe they tested it just to get me to stop talking about it, which has worked up to now : )

[Jerry Adams]

JCH, the reflector is called an Adams reflector : )

[Mario Caceres]

I’m surprised to see all those pictures with the canister sitting directly on the snow.  If you are trying to operate a canister stove on snowy conditions, keeping the canister above the snow will help quite a bit.   Use you shovel if you have one or carry a small piece of close cell foam to put the stove above the snow.

I yet have to try the Moulder Strip, but I normally just put the canister inside a collapsible bowl that I fill with a bit of water.  I keep adding hot water to the bowl once I have to stove going.  Works great.

[Roger Caffin]

Sorry to have to disagree with Bob, but aluminium DOES work fine as a heat shunt.

I have been using aluminium on the stoves I sell and it works well. I have also used it per the previous photos, and it works well there too.

Aluminium is less conductive than copper, but it is also much lighter (lower density). Where you might use a 0.5 mm thick strip of copper, I use a 1.2 mm thick strip of aluminium (or even 1.6 mm thick). I find it useful to shape the strip to match the canister for two reasons: better heat transfer leading to faster reaction, and also the matching curve stabilises the strip against the canister.

Personally, I prefer to clamp the strip fairly tightly against the canister rather than loosely. The better thermal contact gives a faster response time, which can matter in cold conditions.

You need to have 5 mm or so of the strip in the flame to get good heat transfer. Don’t worry that you will melt the aluminium though: it is not going to happen. For a start, many people cook with aluminium pots and have no trouble. The explanation is that the solid (thick) strip conducts heat away down from the tip very fast.

I first mentioned the idea of a heat shunt in my article on the Brunton Stove Stand at the beginning of 2008. Bob Moulder subsequently pushed the idea of the direct attachment to the canister here at BPL, although the idea goes way back in time to when it was called the ‘Alpine Bomb’ in Europe.

Cheers

[Jerry Adams]

Yeah, bowl of water works good.  Although one might consider it a bit fiddly, to have to carry a bowl and put in water.  And keep putting in more water occasionally to cancel the heat to evaporate butane.  And the bowl weighs a little.

With the Moulder strip, you just set it up once then you’re good to go.

The reflector weighs the least, and is less fiddly once you figure out how to shape it so it reflects down to the canister where the fuel is.

An inverted canister stove maybe works at a bit lower temperature.  Most inverted canister stoves weigh a few extra ounces, but Roger’s one is about the same as an upright stove.  They do have a problem that when liquid fuel flows out of the canister, it can carry impurities that clog up the valve.  Getting brand name fuel probably helps.  Maybe you should know how to take the valve apart so you can clean it.

Those threads I gave go into all of this.

What’s best is subjective.

If the snow is 32 F it’s not too bad, because that’s warmer than what’s needed to evaporate butane.  Probably better to set it on something though…

 

[Bob Moulder]

I never claimed to have “invented” the heat shunt, which would of course be ludicrous.

In my very first post some years ago I acknowledged this in the very first paragraph, and included a photo of the typical Alpine Bomb a few posts down-thread. Any time anyone has even faintly mentioned to me the possibility of patent implications I have immediately pointed out that it is not novel and that there is oodles and oodles of prior art.

I merely stumbled across a simpler way to employ it for safe, consistent and efficient use with a topper canister setup. (Which is, by the way, entirely different from using a shunt to warm up liquid fuel from a remote inverted canister where it enters the stove, similar to the common pre-heat tube.)

In this application copper is preferred because the shunt doesn’t have to be so large — which would interfere with some stove supports such as JetBoil — and it is easy to cut and shape it. People can use whatever they want, but if results are less than satisfying it might be worth it to try a proven method that works with plain-jane-butane at -29°C.

However, it is simply inaccurate to say “I tried the Moulder Strip and it didn’t work” when it was done to entirely different spec.

I am not “pushing” anything. I think I did due diligence by being completely transparent in providing details of this method and have been excruciatingly thorough in demonstrating its safety. I have made a few minor changes and refinements and have reported those as they have come along, and other folks such as Gary Dunckel, David Thomas, and David Gardner have also contributed with ideas and testing. When questions arise (as they inevitably do this time of year) about cold weather canister operation, I mention it because it is a viable option. And I am happy to assist anyone who asks.

And while we’re at it, I did not come up with the name Moulder Strip; that would be David Thomas, Master of Memes.

[Mario Caceres]

Jerry, by definition the snow is always going to be below 32F.  My guess well below that most of the time.  Again I normally use a collapsible bowl but those concerned about weight could use a dedicated ziploc bowl which is much lighter.  Just for the sake of it I weighted a ziploc 3 cup bowl at 24 grams (0.8 oz):

But this can be trimmed to 10grams (or 0.35 oz) with walls of 1.5 inch tall which is plenty for this purposes.

Here a picture of a trimmed 3 cup ziploc round container to show it fits perfectly a regular 4oz gas canister.

[Mario Caceres]

As a comparison the Moulder strip / Vecro Strip, per Bob’s own account on the link you posted before is 26.4 grams.  Bowl of water is “fiddly”?, I guess that is a subjective issue.  I find it very easy to put canister inside the bowl and add water as needed.  The best of all … The bowl of water always works  :-)

[JCH]

I just think “Moulder Strip” sounds cool :)

[Roger Caffin]

I cook for two (my wife & me), and so I am able to use a dinner bowl for the water. Zero added mass. But in general, very little mass needed.

Copper vs Aluminium: I have used 1.6 mm thick aluminium as a heat shunt from flame to canister very successfully. Aluminium is a proven material. Possibly harder to cut and shape 1.6 mm Al compared to thin copper, but it is lighter. A thought: one could have big and small strips for the different seasons: very, very cheap to make.

Yeah, let’s blame David T for the name! His shoulders are broad…

No matter the name, Alpine Bomb or Moulder Strip – the idea works and is very simple to set up, and can be light (depending). AND, it avoids the dirt-in-canister problem, which is becoming more serious these days.

Cheers

[Jerry Adams]

That’s what I remember, David Thomas coined the term Moulder Strip.  Bob has been a good sport about it.

David mentioned the technique of putting a BIC lighter under the canister for a few seconds.

I’ve tried most of these.  Different people might prefer one or another.  They’re all good

[Mark Fowler]

Could anybody provide some guidance about minimum size of a Moulder strip when temperatures are never likely to be below 15-20F and using a BRS-3000T or FireMaple 300T. (short burner to canister distance).

Also is it advantageous to have the strip wider at the canister end to enlarge the contact surface?

[Jerry Adams]

Nice implementation Mario, and only 0.35 ounces.

It’s only fiddly in that you have to put in some water, then add some occasionally.  Where you just set up the Moulder Strip and then run it.  Whether that makes any difference to a user is up to the user to decide.  Okay, maybe fiddly is too strong a word : )

Yeah, the Moulder Strip weighs more.

A reflector weighs less, and you don’t have to do anything besides just set it up.  I’ve used it down to 16 F but I know it will work well below that based on measuring it’s temperature.  And that’s with cheap butane, with isobutane fuel like MSR, it’ll work more than 10 F below that:

 

 

[Roger Caffin]

Biased opinion (of course):
Soft aluminium 1.2 – 1.6 mm thick. (or copper 1/2 that thickness)
Strip shaped like a T with a very long stem.
Tip to go 5 – 8 mm into flame.
Width of stem about 10 mm wide
T at base 30 mm wide x 15 mm high
Curve to match canister a smoothly as possible
Clamp to canister as tightly as possible.

I had good result using a #5 hose clamp, but they are very heavy. Others have used a heavy rubber band or similar. A cozy over the lot might, possibly, be of some use.
some insulation under the canister is almost mandatory, be it foam or a bowl of water. A windshield to 1/2 way up the side of the pot naturally.

The foil also works but is a bit more variable and the foil wears out.

Cheers

[Jerry Adams]

15 F – use MSR Isopro or other fuel that is mostly isobutane and you don’t need anything else

it may start slowing down at 15 F when most of the canister is used up.  Have a BIC lighter ready and if it gets too slow, heat the canister up with the BIC for a few seconds.

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