Someone wrote me recently and asked how to make Blue Strobe Rockets. Well, we have a video on the topic (Blue Strobe Rockets, VD0011D), done by Doc Barr, who made the first ones I'd seen. Doc tells me that he first learned about them from John Burdick at a pyro convention in Ithaca, New York. One of the other rocket docs, John Steinberg, was kind enough to write up this description for the guy and gave us permission to reuse it here. Thank you, John.
Blue Strobe Rocket
This is a relatively simple composition to make, but bizarre in its behavior and a mess to formulate. The basic formula is:
Blue Strobe Rocket Formula
Copper oxide, black
GE II Silicone #5000 (bathroom caulk)
First, take the three dry ingredients (ammonium perchlorate (ball milled to a fine dust), copper oxide, and PVC powder) and sieve them together three times through a 40-mesh screen. Then, place them in a container on a balance and tare it. Slowly squeeze in the appropriate weight of silicone caulk. This requires some practice to be precise. Go slow and easy so as not to add too much.
Mixing requires some effort. I prefer to use an old plastic container. First I mix it with a fork as thoroughly as possible. Then, I use a wooden dowel, 1.5 inches in diameter by 6 inches long, as a pestle to try to force the strobe rocket mix through a window screen section stretched over a bowl. Not all will go through, but the kneading action will thoroughly mix even the congealed portion, which can later be grated through a wire mesh screen with 1/4-inch squares.
Some folks like to use a plastic bag of the Ziploc variety to manually knead the strobe rocket mix. I prefer not to be holding it! I always wear gloves and safety glasses when working with any pyrotechnic compositions. And, I sure don't want to make a mess of anyone's shop who is gracious enough to allow me to work in their facilities. This composition is so messy that I recommend you set aside a set of tools to use with this and with nothing else.
The composition is highly flammable as soon as it is mixed, so be careful. Use an arbor or hydraulic press, it is best pressed (do NOT hammer or ram this composition!) into strobe rockets BEFORE it has a chance to set and cure. When it cures, it's like working with small pieces of pencil eraser. Try making cut stars before the mix cures. Or, try pressing the soft composition into tubes for strobe pots and letting them cure overnight.
The composition actually burns quite slowly. Try burning some on the ground, outside a tube to see this effect.
There are many types of silicones. Different curing systems are employed. Some may not be compatible with the other chemicals used. I do not recommend any but the most cautious experimentation with any other silicones. Further, if you place a small amount of composition on a steel plate and hit it with a hammer, you will find it is also shock sensitive.