Ah, a nomanclature problem. When you said flint I thought you meant the rock rather than a bar of ferrocerium.

Sparks from ferrocerium rods are much hotter and appear in significantly larger numbers than sparks tossed by a knife blade hitting flint/chert/petrified wood/etc and so are much more likely to ignite tinder. I was hoping you found something other than char cloth that would work with old school flint/steel strikers.

-Blast