May 05

Electrolysis and camp towels

Max brought a 12V battery and a jar with two tufts of steel wool separated by a sock.  He used baking powder as an electrolyte in the water.  Wiring the jar to the battery worked well, creating enough hydrogen and oxygen to ignite with a match to create the pop you can see and hear in this video:

Max explains how this works:

separating hydrogen and oxygen

When we poured the solution into a jar that separates hydrogen from oxygen (see photo at left), we got little activity.  We suspect that’s because it uses pencils as electrodes, so the surface area is much less than with the steel wool.  Though the graphite cores of pencils are reputed to resist breaking down during the electrolytic reaction, there’s not enough reaction for us, so we may figure out how to connect the pencil cores with steel wool or something similarly rich in surface area.

draining camp towel We experimented with camp towels for a lightweight backpacking trip I plan for late June.  Though we do not have a high-tech towel like Cascade Design’s ultralite camp towel, we tested two candidates from Dollar Tree: microfiber and shammy (reminiscent of chamois).  We measured them and then weighed them dry, soaked in water and dripped for a minute, wrung out, hang dried for an hour in an 80F garage, and hang dried overnight.

While we used a digital scale to weigh the towels initially and after hanging dry (1 hour and overnight), we inferred the intermediate weights, soaked and wrung, by capturing all the water back into the source beaker. Each beaker started with 300 mL before dunking each towel in.  We noted the water height after removing the towel, letting it drip for one minute, and also after wringing. With each mL of water weighing one gram, the math was easy.measuring water left by camp towel Our results are shown in the photo, with the last bit of data missing: overnight drying brought both towels back to their original weight of 29 grams.

Starting and ending weights were the same.  Shammy had more area (260 vs 224 inches squared), but the microfiber was half the price (2 for $1).  Shammy soaked up more water (171 vs 131 g), but both released the same amount of water on wringing (100 g).  An hour hanging got the microfiber a bit drier (down to 44 vs 61 g), which was no surprise because it held less water both soaked and wrung.

camp towel dataThe verdict? Each should soak up the same amount of water (100 g) after each wringing cycle, so that’s a wash.  Shammy soaks up more initially and microfiber releases more.  Unless I had a lot of water to soak up at once and then left the cloth to dry on my pack while hiking, I slightly favor the microfiber because it will be less wet and less weight while drying on my hike. If there’s a lot of water to soak up (perhaps condensation in my bivy sack), then I may need one additional wring-soak cycle with the microfiber to catch up with the shammy’s greater initial absorbence.  The lesser area and the lower price are not significant to me.

The hope? That someone with high-tech camp towels will repeat this experiment and share their results in a comment here.  At $24 for a “large” (and discounts from that), this experiment would be overkill just to avoid cost.  It is justified for the experience of science and for the possibility that additional data from high-tech camp towels will give the public the knowledge to make their own choices between performance and price. If you know any scientifically-playful ultralight backpackers, send them to this blog on the chance they replicate the experiment.

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