Make 'char-cloth' out of the teeshirts before using them.
To make it:
Cut cloth up into small one to two inch squares.
Put them in a sealed metal container(like an Altods' tin.
Punch a SMALL hole in the container.
Put it on a fire OUTSIDE(unless you have a REALLY GOOD vent hood!)
When black smoke STOPS coming out of hole, take it out of fire.
Let cool COMPLETELY(if you do not, when you open the tin, the char-cloth can burst into flame!)
Carefully remove cloth from tin.
Store in airtight(well moisture tight any way) container.
When you need fire, take a piece out, put it in among your tinder(toothpick sized twigs, surrounded by larger twigs, etc.) and just look at it wrong with a spark, and you will have fire!