This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.
From Kevin Kuczek:
> Can someone tell me what "tracking powder" is made of? Can it be
> added to a single use motor to help in seeing the ejection? I have
> seen references for it but nothing to explain what it is.
The BEST tracking powder is epoxy paint pigment. It is used by all US
team FAI altitude and scale altitude flyers. Better than chalk, better
than powdered tempura. When deployed, the clouds are very, very dense
and most importantly, linger for a few seconds so that trackers have a
greater chance of homing in on it. You can purchase at
www.dayglo.com. It's not cheap by any means, but the results are well