My grandmas nephew was severely burned and nearly died in an accident involving grinding under a VW and the mag from the engine burning him.

As far as the vasiline cotton ball with mag goes, thats exactly what I do. I keep the vasiline cotton balls in a film canister, and when ready to use them I shave some mag off my block, and spark it with the sparker on the other side of the block. One night we had got a HUGE rain the day before, the ground was even still a little damp. I still got a fire going no problem with that method. Took some small drier limbs from the underside of a cedar tree and that was all it took to get it going.