Clearly you are safety conscious and wise enough to visit this forum before making it but can I urge you to try making some other compositions first? If indeed this is your first which your original question suggests. It's just that flash is pretty high risk for the less experienced. And it gives fireworks a bit of a bad rep if tested in a built up area.
This isn't my first foray into pyrotechnics (or chemistry) and I've made flash more times than I care to recall. I've usually bought everything already milled and "ready to go" as it were. Just wanted to double check something that wasn't on the MSDS.
I'd rather ask a stupid question and get an answer - than risk an injury. (Remember, there are no stupid questions, only stupid people!)