We also tried impregnating cotton balls with potassium nitrate (by dissolving it in water).

Like the other fuels we've tried, cotton is roughly C_xH_2xO_x-e but the 2:1 oxidizer:fuel ratio was harder to assure. So we guessed.

10g KN_O3 dissolved in 100ml water, soaked 3 4cm diameter cotton balls (~5g total).

The balls were dried for 5 days at 30% relative humidity, 22° C

• On the first day the balls were dense & crispy; they also broke rather than thinning when pulled
• By the 5th day they were light, very crispy, and dry on the inside when pulled apart

They burned, but not impressively (about like regular cotton balls). Slow, smoky, with lots of ash.

Fluffing them helped a little; compressing them didn't do much.