Testing stars
From PyroGuide
 Testing stars is an important step in making fireworks, especially when new star compositions are being used. Testing is simple, and can deter much frustration in the long run. One of the main reasons for testing is to ensure that new starts are not 'blown blind'. This is when the burst charge that should ignite your stars fails, either totally or partially. While testing isn't essential, it isn't hard to do, and an experienced hobbyist will tell you its well worth your time. The most basic testing only determines the color and effect of your star, and not its airborne performance, but this is an important step in quality control and is fairly simple. It is also possible to use this testing to see if your composition is being mixed and formed evenly. A metal bucket works just fine as a container, but any solid surface that will contain a lit star will work. An open surface, while solid, can sometimes pose problems when larger stars are being tested. If the layers of composition are uneven or not well-mixed, the star can propel itself on a totally random path, which isn't a good trait when combustibles are nearby. To test your star even more effectively, you can use a mortar tube, paper tube, or better still a star testing gun. A star testing gun is basically a steel plate with several different sized steel tubes welded vertically to the base. Each tube has a visco fuse hole drilled at the base and enables you to test various sized stars. A very useful tool which basically never wears out. The star testing gun on the right can be purchased from Skylighter. |
 If you are using paper tubes to test, simply plug one end with clay and drill a small visco fuse hole right above the plug. Add a small amount of lift powder into the tube and then drop your star inside (it should be a close fit and not tight). If the star is a very loose fit you will need to add more lift powder. Secure the tube to a solid surface or large piece of wood with hot melt glue or similar. Light the fuse and retire to a safe viewing area. |
 Hopefully your star will perform as required. However, there are some common problems which can cause it to fail. If your star does not ignite it is possible too much lift powder has been used and at effect time the star is moving so fast the flame blows out. Another possibility is your stars may require prime, which is another pyrotechnic composition that encases your star. If your stars are primed, then it is possible the prime is not hot enough to ignite the star. If you find that your stars perform well but, when used in an aerial shell or mine they fail to ignite, it may be possible the stars are being smashed by the break charge or lift charge. There are many reasons why stars do not perform, but following this simple process will help you eliminate most of the common problems. |
 As you can see, it is beneficial to test your stars prior to using them. There is nothing worse than going to all the effort to make your aerial shell, mine etc., and all you get is a loud bang with no or little visual effect. |