Today in the Fire Lab we’ll be taking a very close look at char-cloth. You may recall in the last episode we took some samples of cotton socks and a t-shirt and used hoat coals and relatively airtight chambers to allow pyrolysis but prevent oxidisation, leaving us with sold carbon in cloth form.

Your first lesson in quality is that so-called cotton socks contain a lot of elastic and polyester, often leaving you with results that are so threadbare you can see them with the naked eye.

If we look at this poor-quality, low-yield char cloth being ignited under a microscope, we can see the oxidisation reaction following an individual thread of cotton, but not igniting any of the adjacent threads. What you need for better results is more cotton, with threads that are closer together, and I’ve got to tell you that cotton t-shirts are an improvement over socks, but they are not denim.
T-shirt, jeans.
T-shirt, jeans.

Not stretch jeans. They’re full of elastic and make rubbish char cloth.

Not printed denim. That leaves ink residue that interferes with oxidisation.

What you want is tough baggy old jeans that hang on you like a sack with legs, and make your arse look awful.

THAT is what results in char cloth that gets you these kinds of results.

So, Lesson 1: up your thread count

Lesson 2: for best results, roll and fold

I made this shade-box outside that will allow us to see the beam of focused sunlight I’ll be using to ignite my char cloth, AND the oxidisation reaction that follows.

Let’s start with a flat 4cm square, and you should be able to see immediately how useful char cloth is in lighting fires. It has a low ignition point.

But how do we take this reaction and parlay it into a larger reaction that is intense enough to ignite a fire?

Well, we multiply it. Here’s another flat square that has been folded into quarters, creating a square no more than 2cm across that offers 4 times the heat of a single sheet.

Here is a square that has been rolled tightly into a cylinder, and you can see that this might create a better focused point of heat if it didn’t splay out so readily.

And here is a square that has been rolled tightly into a cylinder and then folded in half. It starts just as readily as anything else we’ve used, only this time we have successfully focused the energy into an area that’s less than 1cm across, and offering up to 8 to 10 times the intensity of the reaction you would get from a single layer of char cloth, and this is the kind of heat you will need to ignite tinder.

So, there’s our closer look at char cloth. Remember to use denim jeans with 100% cotton for better results, and roll and fold your char cloth to focus the heat.

OR you could just buy one of my incredible fire lighting kits. My fire lighters can be lit with a spark, and they do away with all that tinder nonsense, offering you a reliable shortcut to a successful fire in a variety of conditions.

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Thanks for joining me in my enthusiasm for fire.

Cheers all.