Reviews > Lighting > Lanterns > Brunton Liberty Mantleless Lantern > David Sowards-Emmerd > Field Report

Field Report - Brunton Liberty Mantleless Lantern
May 9, 2005

Backpacking Background:
I began backpacking semi-frequently about four years ago, soon after moving to California. I generally take weekend (1 night) trips, and occasionally take 3-4 day trips. Most of my backpacking is at moderate altitude, 6,000'-12,000' (1,800-3,650 m), in conditions ranging from dry desert to hail/heavy snow in the mountains. In winter and spring, I split time between Southern California (SoCal) deserts and snowshoeing/skiing/snowcamping in the Sierra/Cascades. Summer and fall I tend to stick to the high country. I have reduced my packweight down to less than 50 lb (23 kg) over the past year - including food/water and a bear barrel. I'm trying to include more mountaineering, climbing and bouldering in my trips.

The Liberty Lantern arrived on March 1, 2005.

Product Description:

Manufacturer's Description:
''Our award-winning lantern is more than an impressive invention. It's a camping revolution that's changed the way we camp. Liberty is the world's first mantleless lantern. It features a platinum element that is virtually windproof and hassle free. Liberty requires no priming, no mantles and no matches to operate. Light it with one push of a button and reflect light where you need it most. At just over 8 ounces, packing the Liberty is hardly noticeable.''

Manufacturer's Specifications:
''

• 4'' x 2.5'' x 1.3'' (10.2 cm x 6.4 cm x 3.3 cm)
• 8.3 oz (235 g)
• Fuel: Isobutane
• Rating: Approximately 80 watts / 30 candlepower
• Burn time: Up to 6 hours at high output (one 8 oz canister)
• Platinum element instead of traditional mantles
• No fragile glass or plastic components
• Piezo electric ignition
• Built-in reflectors aim the light exactly where you need it
• Includes durable nylon case
• Limited lifetime warranty''

Manufacturer's Warnings and Cautions: (no other place to get these than inside the packaging so far as I can tell)
''

• This product is for outdoor use only. DO NOT use this product indoors or in a vehicle, tent, camper or any other enclosed space.
• Keep the lantern away from the reach of children.
• Never use this unit for any purpose other than providing light.
• Never light or use this product near flammable materials.
• Never Cover the product and/or the fuel canister.
• Never leave the unit unattended while it is in use.
• Never touch the platinum element. The element can be easily bent or damaged. A damaged element may cause improper burning and may result in fire, burns and/or fatal injuries.
• Avoid placing any body parts over the unit while igniting or while the unit is in use.
• Changes in pressure at high altitude and temperature may cause difficulty with the Piezo ignition system. Be certain to always carry matches or a lighter as a backup.
• Use Bruntane fuel canisters only.
• Never attempt to disassemble the unit. This will void the warranty.
• Never store the unit with the fuel canister attached.
• Always keep the unit clean, free of the dust.''

Specifications (as measured by me):
Weight (Lantern only): 7.1 oz / 200 g
Weight (Case): 2.1 oz / 58 g
Dimensions of Case: 5.12'' x 2.75'' x 2'' (13 cm x 7 cm x 5 cm)
Dimensions of Lantern (folded): 4.25'' x 2'' x 1.25' (10.8 cm x 5 cm x 3.2 cm)

Product Description:

The Liberty is a compact, canister-fueled lantern that produces light with a platinum catalyst (similar to a Jon-e handwarmer). For a more detailed description of the lantern, see my Initial Report

Field Testing:

Field testing has taken place both in the field as well as inside and outside my apartment. Testing inside the apartment, I've probably run through a full fuel canister and have not had any problems with the lantern flaring up when moving it around or otherwise. Field testing took place on two snowcamping overnighters:

March 5-6, 2005
Bumpass Hell Parking Lot Area, Lassen Volcanic National Park, CA
Elevation: 8,000' (2,440 m)
Conditions (during use): Windy and temperature probably around freezing

A dozen or so of us headed out on skis and snowshoes for a overnight trip towards Lassen Peak. Several of us dug a large snow kitchen (long trench) so that we could all sit to eat and socialize. Once it was dark out, I fired up the lantern, and placed it on the snow above our kitchen (I was sitting at an end of the table). Unfortunately, the light at the far end of the table was pretty feeble, and when people looked my way (I was cooking up fire-wine), they were most likely blinded by looking at the lantern itself. The effect of the cold on the lantern was very noticeable (I didn't warm the canister under my clothes first): the light constantly flickered, even on high power, and the output was considerably less than what I experienced at home (which is definitely saying something with all the reflective snow around). Igniting the lantern was a bit tricky, and after a few failures with the piezo starter, I broke down and ignited the lantern with a butane lighter. Right after getting the lantern glowing, it flared up once, but then behaved after that. On the way back to my tent, I slipped (damn down booties!) and dropped the extinguished lantern, which was still connected to the canister. The mirrors were still opened and one was bent in the fall, but I was able to bend it back easily once the lantern was cooled down enough to handle directly.

April 30-May 1, 2005
Loch Leven Lakes, Tahoe National Forest, CA
Elevation: 6,800' (2,070 m)
Conditions (during use): Temperature around freezing, with light rain/sleet starting before turning it off.

This was a 3-person snowshoe overnighter. Temperatures dropped rapidly around sunset and I decided to fire up the lantern just before we headed to our sleeping bags. The lantern flared up several times from the yellow/orange glow to blue flames, first soon after I adjusted it for maximum brightness and then again a min or two later. I ran the lantern for another 10-15 min after that while we stood around chatting, and it didn't flare up again during this time. The lantern burned nice and bright, seemingly brighter than on the previous trip. The lantern hissed a bit as the light rain/sleet started up again, and after a few minutes we called it a night. Even with the cool weather, it still seemed to take forever to cool down - I wanted to put it away inside the tent instead of leaving it out in the rain/snow and didn't want it melting my tent or sleeping bag. Also, I did not have any problem lighting the lantern using only the piezo starter.

Testing at Home:
Fuel Burn Rate:

To get an idea of how much life I'd get out of a canister, I did a couple quick burn rate tests. Since I know the maximum gas pressure will decrease as the gas in the canisters is depleted, I did three runs using a range of fuel levels. All three tests were run with the lantern on max power, in my living room (220' (67 m) elevation, 37 degrees north latitude). Snow Peak and MSR 8 oz (237 g) sized canisters were used, and the initial and final weights listed include the canister.

Trial	Temperature	Canister	Initial Weight	Burn Time	Final Weight	Burn Rate
1	72 F (22 C)	Snow Peak	8.61 oz (244 g)	5 min	8.36 oz (237 g)	3.0 oz / hr (1.4 g/min)
2	66 F (19 C)	Snow Peak	6.98 oz (198 g)	10 min	6.70 oz (190 g)	1.68 oz/hr (0.8 g/min)
3	66 F (19 C)	MSR	10.90 oz (309 g)	10 min	10.51 oz (298 g)	2.34 oz/hr (1.1g/min)

So if the 6 hour runtime listed by the manufacturer is valid (I'm not going to waste canisters to test this under different conditions), then the burn rate (and brightness) will considerably lower as the fuel canister is nearly spent.

Cool Down timescale:
Below is a photo of glow after use (2 sec exposure, so it's had some time to cool down during the exposure). Obviously it gets very hot and half a pound (quarter kilo) of metal takes a while to cool down. In my 66 F (19 C) apartment I just ran a quick test to see about how quickly I could put away the lantern. I fired it up and let it run for a few minutes, turned it off and waited. The base was still very hot after 6 minutes and after 9 minutes I was able to very carefully put it away. The reflectors were cool enough to close and unscrew the lantern, carefully latch the regulator wire and put the lantern away in the case. The base, heat sink and protective wires were still very hot, but didn't melt the case when pressed against it. However, unless I'm in a big hurry to put away the lantern, in the field I will definitely wait longer to avoid possibly burning myself.

Focusing the Light:

Below are images of the lantern's beam on the patio fence as well as images of the corresponding mirror positions. On the left, the reflectors are fully extended, and on the right, they are closed in about half way. Clearly, the center of the beam is brighter in the left images, and I would argue this setup is the most focused arrangement of the mirrors. Exposures were set manually and are equal for the two illumination images and the two configuration images. The lantern was placed 6' (2 m) from the wall in the image.

In my long term report, I will try to snap some photos from above the lantern to get a better idea of the overall spread of light.

Miscellaneous:

The Primus PowerGas canister I had sitting around didn't work with the lantern. I could not get more than a small fraction of the element glowing a dark orange - also tried igniting it with a lighter but this didn't do any better. So far, I've had no problems with MSR and Snow Peak canisters.

I'm not sure if the mirrors are plastic or metal (with a low melting point), but I've had a bit of them melt due to the hot guard wire coming in contact with the mirror when putting it away. This is not very noticeable now, but and I will report on it in the Long Term Report.

The epoxy at base of piezo has come unglued from the upper part of the piezo igniter and just slides around on the wire.

In igniting the lantern, converting the blue flame (minimal air flow) to a glow (by adjusting the air flow) doesn't work consistently at high fuel flow. This seems to work more consistently when the fuel flow is low. However, with glove on or even cold fingers it's very easy to turn the gas off completely when trying to adjust the gas flow as the valve is very sensitive.

Things I like:

• It's just a really cool toy!
• Seems fairly well built.
• Easy to ignite and fairly easy to adjust to a nice glow.
• The secondary, lower rubber gasket is a nice idea as a backup against gas leaks.
• Nice for warming up cold hands.

Things I don't like:

• Output is very misleading, most of the output is in heat (an inefficient household 60 W incandescent bulb is considerably brighter, especially considering the broader coverage area of the bulb.
• Color is very yellow/orange.
• It's a bit fickle in the cold (flare-ups and oscillating output - similar to canister stoves at altitude).
• A large fraction of light escapes due to incomplete mirror coverage, much of this light is lost up (it's not 'lost' light if you're trying to illuminate the trees above you...). I contacted the manufacturer about using aluminum foil to supplement the reflectors, but they suggested that was not a good idea due to possible overheating issues.
• Long cool down time (lots of metal mass).
• Adjustment of the gas flow is VERY sensitive. The full range from off to full power is approximately 20 degrees (a full twist would be 360 degrees), thus it is extremely sensitive.
• Temporary blindness caused by looking at the platinum element.

Suggestions for improvement:

• A larger reflector would be nice, especially one that could be detached to achieve a more uniform 360 degree lighting when desired.
• A less sensitive gas valve.

Testing Locations and Test Plan:

I'm still gunning for one more snow trip on which I'll drag the lantern along this spring. After that, the majority of use will be on warmer backpacking and car camping trips in the Sierra Nevada and southern Cascades. Generally, I expect to use the Liberty for lighting up camp and kitchen - this will be interesting since unlike snowcamping, finding a good place to set the lantern (other than on the ground) will be tricky. I may try hanging the lantern with bailing wire. Hopefully, I'll also be able to use the Liberty for some night bouldering in the eastern Sierra this summer - if it's bright enough. Additionally, once I set up a hanging pot apparatus, I will see how long it takes to boil a cup or two of water over the lantern and see if this is anywhere near the efficiency of a stove. I still hope to get a optical spectrum of the lantern so I can determine what fraction of the emission produced is useful light and what fraction is heat. Also, depending on what fuel canisters I have sitting around, I may include some photos of maximum brightness as a function of remaining fuel. One concern I have is how well the lantern dries out if it's left out in the rain overnight or otherwise soaked. Finally, I will keep an eye out for the interaction of bugs with the lantern.

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Reviews > Lighting > Lanterns > Brunton Liberty Mantleless Lantern > David Sowards-Emmerd > Field Report