treating fungus for use with firesteel

[Bushman5]

a while back someone mentioned something abot soaking or treating those big fungus's that grow on trees with a chemical, prior to drying them and using them to catch and hold a spark.

what was that chemical?

 

[halo2]

A source of nitrates: potassium nitrate (saltpeter, found in some stump removers) or urine. have fun.