Testing Firework Stars, Making and Using a Star Gun
We get a small, but constant flow of questions from people who are having various problems with firework stars they are making. Perhaps the most common one is the problem of firework stars being "blown blind". That is, when aerial shells explode in the air, some or all of the firework stars are not igniting. I don't want to go into all of the diagnoses and solutions to this problem. It is discussed in detail in Bill Ofca's book, called "Ignition: Materials, Problems & Solutions".
Over and over I hear from people who are not adequately testing their firework stars before they are assembled into a fireworks device. Almost everyone will test burn his or her firework stars in a static situation, that is, while the firework stars are sitting still. But an amazing number of folks never test fire their firework stars out of a star gun to see how they will perform in the air.
Now a star gun can be just about any makeshift mortar or tube. You can use a simple cardboard tube with just enough clearance for the firework stars to fall down into it freely. Just plug one end of the tube, and drill a visco fuse hole right above the plug. Stick a piece of Visco fuse into the hole; drop a pinch of black powder into the tube, and then a firework star. Light the visco fuse, get back and watch what happens. If your firework stars light, you will be able to see a pretty good approximation of how it will perform in an aerial shell or mines.
If your firework stars don't light, you may have one or more problems. You may have put too much lift powder under your firework stars, propelling the firework stars so fast that the flame actually blows out. Test more firework stars with less powder and see if the firework stars ignite. Remember, if the firework stars are a close fit to the star gun firing tube, then it will only take a very small pinch of powder. If the firework stars still don't light, even with a smaller amount of lift powder, your problem is likely priming. Either the firework stars are not primed or the prime you are using is not hot enough to light the firework stars composition. Again, I refer you to Ofca for more details on priming solutions.
Simple, cardboard-tube firework star guns are cheap, but they have the drawbacks that one size does not fit all firework stars, and that they eventually burn up and come apart, so you have to keep making new ones. At one point in my pyro career I actually had time to make a lot of firework stars. I had my friend John Smith in Baltimore make me up a firework star gun out of steel with five, different-sized barrels: inside diameters of about 3/8 inch, 1/2 inch, 9/16, 3/4, and 1-1/16. He welded the firework star guns in a straight line vertically onto a flat steel plate, drilled Visco fuse holes in the base of each star gun, and even spray painted the whole thing flat black. Neatest firework star gun I have ever had. It doesn't wear out. The different inside diameters of the star gun tubes let me shoot any sized firework stars I make using almost no lift powder. In fact, I can shoot them so silently that my next-door neighbors can't even hear the thing when it fires.
So I got John to make me 10. After two years of selling firework star guns, almost nobody wanted one until recently. Those guys who did buy them loved them and, like me, would never use anything else.
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