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[at-l] Alcohol Lantern Design Theory



> Anyway you prompted me to ask a question that has been "burning" in
> my
> mind since I started backpacking "lighter". Does anyone have a
> design, or
> is it even possible, to make a alcohol lamp out of a soda can, cat
> food
> can or any other cheap method, that will burn the same alcohol that
> we
> are already carrying for our stoves. I am not an engineer but I
> assume if
> it is possible it would need a wick of some kind and a globe. How
> about a
> reflector?

Vic, my man, cheap is a word near and dear to my heart. I have spent most
of the evening in a darkened garage, much to the dismay and concern of my
wife. I've been turning this alcohol lantern idea over in my mind for
several days now and tonight I built version 1.0 and 1.1. And the results
were.............................not good. In both v1.0 and v1.1 the
flame was just weak. By this I mean it did not kick out much light. I'll
offer the details here in anticipation of some input from the List. To
better define "not much light" I'll explain my test standard. I took a
candle that I scrounged from the trash last Christmas and lit it out in
my garage. I found that I could read print that is about 1/8 inch tall
when the page was 3 feet from the candle. When using the flame of version
1.0 and 1.1, I had to move the page to within 9 inches.

Version 1.0 is made from a little "tin can," the sort of lightweight
metal can that shoe polish comes in. It measures 2.75 inches in diameter
by 0.5 tall. The can will not be used for storing alcohol. I went to the
local hardware store and for ten cents I got a cotton wick, the kind that
goes in your garden variety oil lamp. I rummaged through all the junk I
keep here and about looking for some sort of metal tubing from which to
make a holder for the wick. What I finally used was a spent .38 caliber
cartridge. My advice to the world is to never throw away anything.

To start the assembly process, I used the spent cartridge as a hole punch
to cut a neatly formed opening for the wick tube. I put the top half of
the can, the lid if you will, onto the work bench. Using a hammer, I
struck the back end of the cartridge thus driving the open end through
the thin metal of the lid. With just a few light blows, I was able to cut
a hole the exact diameter needed.

I cut the hole near the edge of the can. I chose not to put it in the
middle because I wanted to be able to tilt the can and allow the fuel to
flow to one side. My concern was that when the alcohol was nearly used
up, it would tend to adhere to the sides rather than pool in the center.
After several test burns, I think it will work just fine if the hole is
centered in the middle of the lid. Apparently, alcohol doesn't have the
cohesive properties of water.

The next step was to cut off the rear end of the spent cartridge so it
became a tube. I love my little drimmel tool. The purpose for the wick
tube is to keep the open flame away from the can. By rolling the wick, I
was able to put it through the metal tube with ease. The tube is half an
inch long. With about 1/4 inch of the wick protruding from the top, I cut
off the rest. The piece of wick I am using is about one inch long.

After cutting the tube to length, the next step was to solder it to the
lid. I didn't want any opening around the wick tube where fumes could
leak out. The difference between version 1.0 and 1.1 is the soldering. In
1.1 I removed the solder to see if alcohol fumes leaked. I think there
was no leak because I couldn't see any flame at the hole in the lid. The
only fire was coming from the wick. This is good because it eliminates
the most tedious step, that of soldering.

There is another advantage to v1.1. The tube can be removed from the hole
in the lid and stored inside the can when not in use. This will make the
lantern much easier to pack. In forthcoming experiments, I'll try using
the lantern without a wick tube. In the current configuration, I find
that even after the flame has been burning for 10 minutes, the can does
not get very hot. I can pick it up and hold it without burning my
fingers. If the flame is allow to be near the lid, I'm not sure how hot
the can will become. The wick tube holds the flame about 1/4 inch from
the lid.

In my test burns I put 1 ounce of denatured alcohol in the lantern. I
found that this amount of fuel would burn between 25 and 28 minutes. I'm
sure the difference in burn time comes from inaccurate measurement of the
alcohol I used. The lantern, wick, tube and reflector (6x6 piece of
aluminum foil) weighs just a tab over 0.5 ounce. I used a little kitchen
scale. By comparison, my candle measures 7/8 inch in diameter and is 5
inches long; it weighs about 2 ounces. I marked the candle in 1/4 inch
increments and find that its rate of burn is about 1/4 inch in 15
minutes. This is consistent with previous tests using different candles.
My rule of thumb for candles is about one inch per hour.

The building and experimenting have been fun, but the results thus far
favor continued use of the trusty old candle. The goal is to develop a
light weigh, durable, simple to make, simple to maintain, inexpensive
lantern that burns denatured alcohol. Obviously the lantern must match
the brilliance of a candle or there is no point in having it. Right now,
I'm not able to get much light from my lantern.

Will version 1.2 burn bright? Will Hopeful ever emerge from the dark
garage? Will Mrs. Hopeful have him committed? Tune in next week for
another exciting episode of Hopeful And His Trusty Drillpress. Brought to
you by The American Shoepolish Can Manufacturers's Guild.

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