I've had the same problems with humidity, but have found another thing that also works well. I put in a small piece of tissue paper (ie. kleenex) and one match head - partially broken up. It gives a nice flash. Sometimes it's strong enough to push the piston out of the tube, but it's not that powerful...but just in case, keep your face/body away from the plunger.
Have a great day!
Dwight Souder
Crestview HS
Ashland, OH
This message was sent using 100% recycled electrons.
________________________________
From: phys-l-bounces@carnot.physics.buffalo.edu on behalf of David Willey
Sent: Tue 1/19/2010 10:57 PM
To: Forum for Physics Educators
Subject: Re: [Phys-l] fire pistons
If, like me, you often have humid days that make it difficult to get
your fire piston to light a small scrap of toilet tissue, try flash
paper. It's available from magic supply stores and works really well.
DO NOT however do what I did and use close to a square centimeter of it.
Ten square millimeters is about the maximum you need to use, a hundred
blows up the piston and the protective tube.
Got to love safety shields and goggles, be safe,
cheers,
David