My experience with cotton balls and flint and steel is, they suck at turning an ember into a flame. They'll light but they're much more miss then hit. What I found to be a far superior material is jute twine. The cheap brown stuff that doesn't make particularly good cordage. A short piece, unraveled and bunched up catches with barely any work at all. Don't know why cotton has such a hard time igniting. I suspect the fibers are too fine, but that's not even a hypothesis.