Sharpen the pencil and create a bunch of tiny shavings then put them in a pure O² environment. They'll light up real fast.

Tbe Apollo 1 fire spread so quickly because in a pure O² environment fucking velcro was super flammable.

Finer bits of wood, like sawdust, or pencil shavings from sharpening, catch fire much more readily than a solid chunk of wood like a whole pencil.

Given the right environment, finer sawdust can even be explosive.

A lot of campers and other outdoorsy types are probably familiar with using "feather sticks" to start a fire, where you take a stick and cut a bunch of fine curls into it, almost like you're whittling down the stick but leaving the shavings attached.

The whole stick wouldn't readily catch fire, but those finer curls attached to it will light pretty easily and spread to the rest of the stick.

And while I've seen some pretty impressive feather sticks made by people with a steady hand and sharp knife, most of the time those feathers aren't quite as fine as most pencil shavings.

Yeah, try lighting your pencil on fire in a 100% O2 environment. It's not the pencil being flammable that was dangerous, it was the pure oxygen atmosphere making the pencil extremely flammable to the point where a small spark from static electricity could cause it to almost instantly immolate, that made it dangerous.