You may not be concerned with safety when you first start your pyrotechnics adventure, but you will quickly realize how important it is. Below are some tips and tricks, and general safety information that I picked up from different sources.
Treat this powder like the most dangerous stuff on the earth. Explosive powders (IE flash/whistle mix) are how people kill/maim themselves in pyrotechnics.
Mixing the compositions - You should never screen these things together. Get both powders very fine and then diaper them together. You can add some cab-o-sil to the flash powder to keep it from clumping. The diaper method involves dumping the powders on newspaper and rocking it back and forth gently until it is mixed.
Never mix too much flash powder - How much is too much? If you are an amateur, more than 10 grams is too much. If you are a pro, more than 50 grams is to much. This stuff can explode unconfined so be careful.
Never use metal tooling - Metal tooling can spark and cause this stuff to explode, killing you with shrapnel. NEVER use sparking metal rams/screens/casings/or anything else made of sparking metal when working with flash/whistle mix. Non sparking rods are fine when pressing whistles.
Consolidation - Never consolidate flash! There is no need to press/ram this stuff unless you are unhappy with living. Never ram whistle mix. It will explode and kill you, only press this mix in small increments.
Be afraid - Treat all devices you make with flash/whistle mix as pipe bombs. Would you light a pipe bomb in your hand? Would you stand five feet away from a pipe bomb when it goes off? You shouldn't do these things with devices containing flash/whistle mix either.
Even if you are working with gunpowder (an edible pyrotechnic compound) you need to wear dust protection. Though the dusts aren't specifically toxic, they can irritate your respiratory tract like anything else. I wear special Moldex 2500N95 particulate respirators. These are dust masks on crack that eliminate the risk of breathing hazardous stuff. You can order these or similar from a variety of suppliers on the Internet, make sure to splurge on these. You can reuse them many times when only using them for pyrotechnics applications, and they can save your life!
Some pyro chemicals are extremely toxic. Inhaling just a little lead tetraoxide (a dragon egg component) dust can kill you. Lead poisoning is not a pleasant way to die. Treat all pyro components like lead tetraoxide, there are other things that are just as toxic.
Latex glove are a pyro's friend! Especially if you have cuts on your hands like the ones I get from dried sodium silicate all the time. Some compos (like BP) sting quite a bit in little cuts like these. Certain chemicals can also irritate the skin, so latex gloves help quite a bit. Latex gloves won't help you when working with acetone and other solvents because they will dissolve. You'll need special gloves for working with these.
Fix up look sharp! When I was in 6th grade my science fair project's goal was to determine the ideal flame resistent fabric. I tested over 50 fabrics with a barrage of tests: open flame, light bulb, torch, cigarette, etc. Cotton ranked the best. Synthetics like polyester were the worst. Always wear protective cotton clothing when working. A cotton baseball cap or other hat will help protect your very flammable hair from ignition.
Leather or similar gloves will help in the event of accidental ignition. I use MechanixWear Mpact II gloves. They also make a gauntlet that might be useful in pyrotechnics.
Always work in a well ventilated area - If composition dust builds up in the room you are using, its surface area could be very great and in turn very explosive.
Beware of floating dust! - Though you may not be able to light your 2 micron aluminum or other pyro fuel by itself on a pile on the ground, it is extremely explosive when floating in the air. It also has a very low ignition point with a greater surface area. It is best to work with more dangerous fuels (dark al, mg, etc.) outdoors.
Eliminate static - Those little cans of static spray that you have in your laundry room and never use have found a new purpose; they can save your life! These sprays actually do eliminate static, so spray the shit out of everything and eliminate all the static in your workplace. Grounding yourself with a simple grounding wristband (you can find them at computer stores) will help as well.
Beware of sparking electrical equipment - Powertools have many uses in pyrotechnics, but a lot of them generate an amazing amount of sparks. These sparks can kill you when mixed with pyro compositions or dust in the air, always use these tools outside and away from your workplace.
Are you a smoker? - Smoking will kill you, but it'll happen much quicker if you are a pyrotechnician. I quit smoking, you can too if you want to be a pyrotechnician.
A discussion occurred on rec.pyrotechnics about this topic. Sealing tubes is a tricky thing to do when they contain sensitive material.
If your tube contains flash powder - You should never consolidate flash, it is far to sensitive. If you are making an M-80 or similar device, you don't need to seal the tube very tightly, simple paper endcaps will work. If you wish to seal them better, use some sodium silicate to seal the paper cap in. Do not ram clay!!! It'll be the last clay you ram.
If your tube contains whistle mix - If you are making a salute/m-80, follow the directions for flash. If you are making a whistle, you should press (never ram) the composition. You will only need to seal one end of the tube in this situation, do it before you pour in the flash.
If your tube contains any other sensitive composition - You can use hot glue, it will almost never ignite what you are using. One safety tip though, from Don and Robert Goodman on rec.pyrotechnics, plug your glue gun into a surge protector or foot pedal and turn it off when applying the glue to the tube. If your glue gun shorts out it becomes a spark gun. The sparks could ignite they compo you are working with and kill you.
If your tube contains any other composition - IE Smoke mix or something that won't hurt you if it ignites while sealing, just use hot glue! No need to unplug the gun either.
Things to worry about with different compos:
Always avoid using metal tooling when possible.
Glue guns can short and spark, so be careful when using them. If possible, plug them into a switch/foot pedal and turn them off when applying glue. Do not worry about applying glue directly to composition.
