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Are you refering to dispersing a cloud of the powder and igniting it?  I
have done the demo with several powders and found that corn starch works
very well, but the best results are with lycopodium powder (a pollen I
think), it is expensive, but it doesn't take much and provides a huge bang
for the buck.  Flour must be dried in the oven first for a decent effect.

I have typically used a funnel attached to a length of plastic tubing and a
candle or open flame burner as an ignition source.  Set up the funnel so
that it points upward and toward the flame source (the distance depends upon
a lot of factors, but about 20 - 30 cm is a good place to start), put some
of the powder into the funnel (maybe 30 - 40 grams), then blow through the
tubing.  A cloud of powder comes out of the funnel, is ignited by the flame,
and creates a puff of fire.  For a real show stopper, we followed this demo
up by putting the whole set-up inside a paint bucket, sealing the lid and
letting it do its thing.  The effect is similar to the old flour silos that
would explode; the lid blows off with a huge 'bang' and a flash of flame.
We had to tie the lid down so that it did not fly into the crowd.

Scott Randol
BlueCrowConsulting.com


----Original Message Follows----
From: "Fisher, Martin" <[log in to unmask]>
Reply-To: Informal Science Education Network

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