I have been making char cloth for many years, of various materials of 100% cotton. Old cotton sheets and pillow cases, wornout jeans, tee shirts, worn out flannel shirts, etc. Several years ago I found an ancient 100% cotton, terry cloth towel that had been in the back of our linen closet for years. It had a couple holes in it an my wife was going to toss it.
I grabbed it, cut a bunch of 3"x3" pieces and put them into a tin with lid I'd long used for making char cloth. Put it over my propane camp stove and "cooked it."
After everything had cooled, took one piece and struck one lick on my ferro stick and voila! A great "glow." Stuck it in some tender, blew on it a bit and immediate fire.
So, if you have an old 100% cotton terry cloth towel you're gonna toss, give it a try. You'll find it makes great char cloth.
BTW, I started making char cloth in the Boy Scouts many, many years ago, when our "char cloth cooking can" was a Prince Albert tobacco can.

We used
real flint to strike a spark into the char cloth.
Good Luck.
L.W.