LAB: Tinder Stick

05/20/2015 Update: I will eventually build one of these things..

10/23/2014 Update: I need to finish building this! I had to get a few more supplies and my dad even sent me homemade carbon paper.. I got way too discouraged last spring because I thought it wouldn't work. I hope to have a finished one by this year. Please begin reading my experiment below which I started in late 2012.

So recently, I've been attempting to build a fire piston which is a tool used to start fires. First of all, I'm gonna start calling the fire piston a Tinder Stick just because. So, the Tinder Stick can be referred to as a fire syringe and has ancient roots in South East Asian and other native cultures (wiki). They made these things out of animal bones. Primitive genius' right there! I stumbled upon a DIY project online, which entailed building a vacuum piston out of hardware store materials. Instantly, my crafty self had to make one too.

To make it work:

The Tinder Stick looks like a syringe, except the bottom doesn't squirt out liquids. It is actually sealed off and that's what creates the vacuum. You push down on its top and the tinder, attached at the bottom within the vacuum cavity, flash ignites. This creates a super hot smoldering ember which you can then pull out and put on a separate pile of tinder/wood and use to start a fire.

Why it works:

The rapid pressing motion of the top uses the thermodynamic process of adiabatic compression. This process allows none of the heat created by the compression of air to exchange/dissipate within the environment (outside of the tube). The now un-equilibrized system heats up the air to extreme temperatures, allowing the material within it to set fire. So basically, the rapid pressure increase from pushing down the top will increase the temperature enough to ignite the tinder within, creating a coal. Vua-lah! Fire!

You would be able to calculate the actual values of pressure-temperature change using the simple and beautiful Ideal Gas Law equation:


where P=pressure, ρ=density, R=constant, T=temperature

So if I were to calculate the actual temperatures within my Tinder Stick, you would see an increase from about 20°C (room temp) to about 260°C in a matter for milliseconds. However, I let wiki do that for me.

Even though I finally created a good enough seal to form the vacuum, I must find certain materials to use as tinder that can combust at temperatures with my Tinder Stick. I've read that there are lots of organic fungusesssuses and wood types you can find outdoors that work perfectly. Sadly, something like a piece of paper towel will not work. I have not tried it but I don't think the processed and chemically bleached paper pulp can ignite at the provided temperature. As soon as I find some tinder, I'm sure my Tinder Stick will work.

Why I took the time to make one of these:

I took two quarters of atmospheric thermodynamics this year, learning about the dynamics of air parcels. Reciting equations over and over again was pretty dry, but actually applying this knowledge and seeing the processes work outside of the classroom is more rewarding than a hangover. And I like to hike. It could be super useful on my backpacking trips.

Some photos:

Yep. That's all it is.
Best idea ever to use bottle caps as the handle. #Deschutes
The chamber.

#fire #thermo #ilovethermo #atmos #nerd #bears #deschutes

1 comment:

  1. Well can do it all. I love to find old artifacts and astronomy. If my health was better. I'm only 46 yrs old but, I am disabled. But, I am more of a musician then anything. I can still play my bass, like Geddy Lee or Rush.