Actually, the very best stuff I ever had for making charcloth was the leftovers from machine shop cotton rags/towels that had been used and laundered soooooo many times that they were discarded as not good enough anymore for sopping up oil/grease. There were almost nothing left but bunches of threads! Those multiple washings with harsh detergents to remove the grease/oil really broke down the cotton thread fibers - which were now over twice the size they originally were when woven up into those shop rags. It was almost like charring cotton balls, but still having something left after you "charred" it. (Cotton balls just seem to ... disappear ... when you try to make charcloth out of them.)
Right now, I mostly use something called Monk's Cloth that I bought form WallyWorld. It's a pure cotton thick thread coarse weave cloth - in a standard 5 over 5 under checkerboard type weave. It works well for me.
The best stuff I ever used came from a well washed and worn cotton grain sack. Coarse weave of thick threads, but well worn and washed. That "wear" seems to loosen up the fibers in the threads and make it easier to catch sparks when charred. But if you char it too far or too long, it gets stiff/crumbly and falls apart on me.
My latest way to make charcloth is a method my friend came up with that does not use any "tin". You wrap strips of cotton cloth around a small green stick until you have it an inch or two thick. Kind of looks like you are going to make a torch. Then I lay it on the coals of my fire. When it is all burning fairly well, I take it out, check to see how much of the cloth is "glowing", and then bury it in dirt to smother the bundle.
Once it is out, I dig it up. The outside will be well charred, possibly too charred. But it gets progressively less "charred" as you unroll it. To use, I unroll a couple inches, tear it off, and strike my sparks into it. As I use it up, the cloth starts to turn from black charred to shades of brown. At that point it will be much harder to catch a spark in it. So I just burn it some more in the fire to "char" more of it.
I cut the stick off fairly close to the cloth, and I store it all in a canvas/leather pouch. The stick helps hold and protect the charcloth. The pouch helps keep the mess somewhat contained.
So you don't even need a "tin" to make charcloth. Yes, you do burn up and lose some of your cloth, but scrap cloth is pretty easy to come up with. But I'm also shifting over to mostly using Tinder Fungus or already charred chunks of punky wood to catch my sparks. I'm doing this because most of my stuff is Historically based, and documentation for use of charcloth is almost non-existant before the mid to late 1800's. So we can't find references to people using it back in the 1700's - thus we have to find other options - like the tinder fungus or pre-charred wood/fungus.
Just my humble rambling thoughts to share. Take them as such.
Mikey - yee ol' grumpy German blacksmith out in the Hinterlands
