Re: Can I safely make my own colored road flares?

Your question is a good one.  I have to provide you a long answer to help 
you and others understand some of the issues involved with this type of 
activity.

Road flares are kissing cousins to other types of pyrotechnic formulations 
which are commonly referred to as fireworks, propellants, and explosives.  
Road flares are probably the least dangerous of these types of mixtures, so 
if you attempt to make them, and do something wrong, the resulting 
formulation likely is going to be more dangerous than what you intended to 
make.  The flares consist of a mixture of oxidizer and fuels.  Typically 
various types of nitrate salts, such as barium, strontium and others are 
included in these formulations to give the flames colors which are 
characteristic of the different chemicals.  The problem is that nitrates as 
well as other oxidizers when mixed with fuels can give a variety of 
combustion rates which depend upon particle size, the degree of mixing 
between the different ingredients, the extent of compaction, the presence 
of small amounts of catalysts etc.  When you change the density of a 
particular formulation, it may either burn in a "slow" controlled rate, as 
in the solid rocket boosters used in the space shuttle, or you can get the 
very same formulation to detonate, turning to high pressure gas in a couple 
of microseconds.

The companies which manufacture these types of materials have strict limits 
on how many people can be in a building at a time (to limit the number of 
bodies which must be accounted for if something goes wrong).  They also 
have designed and regularly inspect all of their mixing equipment and other 
facilities to make sure that sparks are not produced, that everything is 
grounded properly, and that no sources of ignition are present.  For 
example, at the company that I used to work for, there were no light 
switches within the building, and any new type of formulation was first 
mixed up remotely in a blast hood.  If the mixture initially appeared 
stable, we would test the mixture for thermal stability, sensitivity to 
friction, sensitivity to impact, as well as other testing to make sure that 
what we were making was stable enough to make larger quantities for further 
characterization and testing.  Even if you find a formula for making a 
particular material out of a book, there is no way that you can be sure 
that you are using materials with the same particle size, purity, or that 
you are performing the same degree of mixing.  Making pyrotechnics is not 
the same as baking cookies.

The last issue I need to address is most serious.  Mixing oxidizer and 
fuels together is legally considered the manufacture of explosives or 
propellants by the Bureau of Alcohol, Firearms, and Tobacco. There are 
federal laws which determine what is the maximum quantity of these 
materials which can be mixed together before you need an explosive license 
(call them and ask).  You can get an explosives license to manufacture 
these types of materials, but the ATF will have to come and inspect your 
facilities along with your storage facilities to make sure that you are in 
compliance with federal laws.  Then you need to make sure that the location 
in which you are making these materials is zoned for that type of activity. 

What usually happens when people don't get proper approvals and permits is 
that they start experimenting, there is a little fire, the fire trucks 
arrive because your neighbors wonder what all of the smoke is from, and in 
the ensuing investigation, you get to talk to all of the regulatory 
authorities, you get to spend time making new friends behind bars, and you 
get to form new business arrangements with attorneys and bail bondsmen.

So in answer to your question, can you safely manufacture these 
formulations? No.

Is such manufacturing cost effective? No.

One last personal observation:  After making and using commercial 
explosives for five years, I still scarred by thumb and forefinger when 
attempting to reposition an igniter in a commercial flash powder mixture 
when attempting to impress an audience.

My recommendations:  Buy the crystals commercially available for coloring 
flames different colors, or forget the pyrotechnics and tell the kids a 
scary story which will keep them awake all night.   Or consult the 
newsgroups involved with pyrotechnics and live dangerously.