Good morning and welcome to Summit Up, the world’s only daily column wondering about the melting point of marshmallows.
We got to pondering this question after watching a fifth-grader build a makeshift solar oven out of cardboard, aluminum foil, two-by-fours, some clear plastic sheeting and a can of black spray paint.
The project, part of a science lesson on solar energy, was aimed at designing an oven that could make a S’more, the ever-popular graham cracker-chocolate-marshmallow concoction.
Seemed to us that was fairly ambitious for a grade-school project, but the kids really got into it, some using mirrors, others trying magnifying glasses, all to reach that critical temperature, which as far as we can tell, is somewhere around 400 degrees Fahrenheit.
We’re not sure about this, but we’re thinking that, since you have to put a marshmallow directly above the flame of a campfire to get that golden-brown, flame-tinged look and feel, it needs to get pretty darn hot.
So while our fifth-grader was at school, our curiosity got the better of us. For starters, we took a basic thermometer and set it out in the cardboard solar oven in some backyard sunshine.
We did run into some technical difficulties right off the bat, as this was one of those medical-type thermometers with a timer, the kind you put under someone’s armpit when you suspect they have a fever.
This may work well when you’re trying to see if someone has contracted hantavirus or whatever, but we’re not sure it’s the best instrument to use for testing the heat level in a solar oven.
But based on our rudimentary observations, it seemed that the inside of the oven was at least getting up to about 98 degrees or so, which is respectable, considering the outside air temperature was in the 50s.
Then, we turned our kitchen oven to 100 degrees and put a marshmallow inside it to see if would melt at that temperature. At the same time, we put another marshmallow inside the solar oven. We figure that, if we were going to do experiments, we might as well use a control, just the way real scientists do.
We left ’em in there for, oh, probably, about 30 minutes or so and when we came back to check, the marshmallows were definitely a bit soft to the touch, but not quite melted to the point of gooey perfection that would make for a first-class S’more.
At this point, we need to add that our fifth-grader pretty much did all the design and construction alone, without much help, guidance or other unwanted adult interference.
It wasn’t until well after completion of the project that we went back and tried to figure out how we could really get a solar oven cranking, and once we started scoping it out on the web, we realized where we went wrong. We were focused on black, thinking that was really the way to get things heated up. But it turns out that reflection is the key, with efficient solar ovens using mirrors and foil to focus all that sunlight on to the cooking area.
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