Roll no larger than 5/16″ dia or stars will strobe all the way to the ground. It is important that the barium nitrate be finely powdered. If your barium nitrate looks like table salt then you will need to ball mill it otherwise the formula may not strobe at all. Using finer magnalium will increase the strobe rate. Going above 300 mesh will give more of a shimmering effect than a strobe effect, due to the high flash rate.