Reposted with permission from Passfire.
The recent fatal accident involving Tad Kolwicz was a harsh reminder of the potential we all face when things go wrong. For those who may be reading this at a future date when the details of this incident have faded into the past, Tad was working in his garage based fireworks shop when an explosion occurred, which blew up the garage and burned Tad so severely that he died after being taken to the hospital. Tad was a rather well known pyro hobbyist who did not build anything on a grand scale. He was not a flash junkie and favored smaller shells in the 4″ range. He was a Passfire subscriber and participated in many forums, thus he was not suffering from a lack of information. These facts are what made Tads accident so haunting. If Tad was cautious, informed and not a reckless bomb maker, how could this happen?
When I first heard of Tad’s accident, I wondered not if it was something I wrote about in Passfire that might have contributed to the accident, but rather if it was something I didn’t write about but should have. Some basic safety information that just never made it into print which might have saved him. While safety tips are scattered throughout the various articles in addition to the accident analysis articles that have been written, there is no single comprehensive article someone could use as a starting point to guide them through the most common hazards of this hobby. That is the goal of this article, which is dedicated to the memory of Tad Kolwicz in the hopes that it may help prevent similar accidents in the future.
The safety tips given here are divided into three areas: containment, prevention and preparedness. Containment involves designing your work area and methods in a way that minimizes damage when an accident does occur. Prevention involves methods that lower the probability of an accident occurring in the first place. Preparedness means being ready for the worst if something goes wrong.
While every effort should be made to prevent accidents, there is no way to ever completely eliminate the possibility that something will go wrong. There are just no guarantees in the real world no matter how hard you try. The idea behind containment efforts is to first acknowledge the fact that some day something will go wrong, then turn your attention towards minimizing the possible damage it will cause. The basic principles of containment are perhaps the most ignored by the pyro hobbyist, usually due to the nature of the workshop or area where fireworks are being built.
Separation of Process and Storage
The separation of completed products from the area in which you normally conduct assembly is the number one rule of containment. Completed products include not only finished items that are ready to shoot, but also stars, burst charge, match and other easily ignitable items that will produce flash fires if ignited. In fact, it is the exposed and easily ignitable nature of stars and other components that actually make them even more hazardous than completed shells. They are the most likely starting point of a runaway flash fire, and can even cause an explosion by themselves if the quantity is large enough.
The magazine is the principle element of containment, which is why the ATF places so much emphasis on it. The concept of the magazine is to remove high-energy materials away from where people normally reside or work and place them far enough away that nothing would be damaged if they did go high order. Granted if anything ever happened inside the magazine while you were inside it, then your chances of injury would be very high. But the percentage of your time spent in your shop is far greater and thus your overall chances of getting hurt are drastically reduced by the use of a magazine.
The biggest problems hobbyists encounter with magazines is having the place to put one. The unfortunate reality of our ever growing population density makes the luxury of having large plots of land increasingly expensive and hard to come by. Many hobbyists are forced to work out of attached garages and other dwellings that are far too close to either their own home or others. However, even a small magazine out in your backyard is better than storing energetic material in your shop or, even worse, your home. Even if your magazine can not meet ATF distance requirements, it is still beneficial to your safety to build one anyway and start using it.
When an accident occurs inside of a building, the building itself acts like a shell casing. This containment results in an increased pressure that propagates the flash fire and raises temperatures even further, thus making a bad situation worse. Then there is the additional hazards of the building collapsing on you if the walls blow out. Most buildings are not designed to withstand pressure forces from within, and getting pinned by a falling roof can make an otherwise survivable situation fatal. Any kind of flash fire, even a small one, is going to fill the air with smoke that will lower your visibility to zero even if the flash of light doesn’t temporarily blind you first. Trying to fumble your way to safety from a burning building is drastically more difficult when blind.
The best place to build fireworks is out in the open air in a shaded area. This is especially true for dust prone activites like mixing chemicals together or rolling stars. If these processes are done indoors, the unavoidable dust will settle on everything in your shop and make the environment even more hazardous. But even without the dust problem, working outside eliminates the hazards caused by enclosed overhead environments when things go wrong. A tent may be used to provide shade without incurring any additional risks, since the sides are all open and collapse is not an issue.
Note that some chemical combinations may become more sensitive if exposed to direct sunlight, such as chlorate compositions. This is why shade is recommended. Sunlight has also been known to cause ignitions with compositions stored in round metal bowls left in the sun, possibly through parabolic focusing of the sunlight through reflection. Shiny metal bowls should thus be avoided altogether as a container for holding pyrotechnic compositions.
Unlike professional manufacturing operations, the hobbyist does not have to keep producing if the weather outside is not cooperative. If rain or cold weather prevents you from working outside, then it is better to just wait for it to clear up. I realize this may be difficult for those living in Northern regions who are subjected to frozen tundra for half the year, but cold weather also brings with it a static electricity hazard that is further reason to wait for more favorable conditions in which to make pyro. If you simply must do pyro year around in an environment such as this, it would be a good idea to get all your stars and chemicals mixed in the summer months so that only the assembly operations would need to be done in cold, dry weather.
When you must work inside a building, try to keep it as open as possible. By opening things like doors, garage doors and windows, you reduce the ability for pressure to build up and thus reduce the chances of a building collapse. Having large openings like open garage doors also makes it easier to escape the building under blind conditions. Many commercial assembly buildings do not even have doors and have multiple exits so that a blinded worker can escape in multiple directions.
Sealed Storage Containers
The containers used to store raw materials such as stars, burst charge and composition also play a key role in containment safety. These containers should be sturdy enough to withstand a brief flash fire without the internal contents igniting. Standard five gallon plastic pails are most commonly used for this. Some five gallon buckets have a rubber seal in the lid, while others do not. Without the seal, a closed bucket subjected to the hot gas pressures of an indoor flash fire would still ignite. Sealed lids have been found to prevent ignition and thus reduce the impact of flash fires in commercial accidents. A very nice type of screw-on lid adapter for five gallon buckets is sold by PyroSupplies or U.S. Plastics.
It is pretty common for hobbyists to store stars in plastic zip-lock bags. This is very convenient due to how cheap they are and how many different types of stars one typically accumulates. Having a plastic or paper container for each type of star would take up a lot of space and get expensive. The thing to do in this case would be to store the bags themselves into large sealable containers. Old empty perchlorate drums make good containers also, and are more fire resistant since they are made from metal. The down side to metal containers would be the potential shrapnel generated should a reaction ever initiate from inside the drum.
Minimize Exposed Material
When engaged in assembly operations and other activities where energetic material must be present, it is important to minimize the amount of material that is exposed out in the open. Any material that is not needed for the project at hand should not even be in the room, even if it is in a closed container. By limiting the amount of material that a flash fire can feed on, you minimize the size and destruction an accidental ignition is capable of producing. If you are working in a small space with a large rack of stars drying in one part of the room, a table top full of rough powder drying behind you, a bunch of black match sitting on the table and open buckets full of burst charge and stars sitting around, your chances of survival are much more limited if something ignites.
These tips represent the basic rules for preventing the most common accidents from happening in the first place. Given the low accident rate among pyro hobbyists, I would say most people do pretty good in this area. Knowledge of the most sensitive chemical combinations has been discussed eternally on the popular forums. An overall sense of self preservation combined with common sense will prevent many things mentioned here.
Among the most scary prospects for the new pyro is accidentally mixing a hazardous combination of chemicals together that may spontaneously combust. Unfortunately this is a real concern, as there are several combinations that will either combust outright or increase the sensitivity to a point where triggering an ignition becomes dangerously easy. The best advice for someone starting out is not to experiment on your own, rather follow formulas that are known to be safe such as those listed in the Passfire formula database. “Safe” is of course always a relative term in pyro, but in this context it refers to chemical combinations that are stable to work with and will not spontaneously ignite under the levels of friction and shock that occur during mixing, handling and general use.
Before listing the chemical combinations to beware of, one specific chemical needs to be singled out: chlorate. Almost every problematic chemical combination in fireworks usually involves a chlorate compound. Potassium Chlorate and Barium Chlorate are two of the most widely used chlorates in fireworks, and have been around for a very long time. There is perhaps an unsubstantiated level of fear among hobbyists regarding chlorates, but then too much caution never hurt anyone. The use of chlorates in itself does not guarantee an accident, rather it increases the probability of an accident by increasing the number of precautions that must be taken. The more safety precautions you must take, the higher the chances become that you will forget one at some point and have an accident. Some fireworks manufacturers have used chlorates for decades without ever having an accident, and the fireworks made in Malta and Mexico still use chlorates as the primary oxidizer to this day. The Maltese even push their Chlorate use to the very edge by using combinations that include sulfur, antimony and even magnesium– combinations you will see ranked as Hazardous below.
While chlorates can be used with a degree of safety that is proportional to your degree of caution, it is highly recommended that people new to pyrotechnics avoid using them until they have a good deal of experience. There are too many precautions to adequately cover in this article. However, a very good book has been written exclusively on this subject which should be mandatory reading for anyone thinking about getting into chlorates: Technique in Fire, Vol 10: Working Safely With Chlorates by Bill Ofca.
The following chemical combinations are organized into three groups: Extremely Hazardous, Hazardous and Mildly Hazardous. The extreme group represents combinations that will very likely hurt you no matter how careful you are. The Hazardous group can be managed without incident, but will involve a level of risk that is likely greater than the average hobbyist is (or should be) willing to accept. The mild group still involves increased risk due to increased sensitivity, but the risks are a lot more manageable.
The word “Chlorate” below implies both potassium chlorate and barium chlorate. The barium chlorate compound is actually the more sensitive of the two.
Any Ammonium compound combined with any Chlorate compound
(NOTE: The ammonium chlorate risk is so hazardous that even stars with ammonium and chlorate compounds located in different layers should be avoided. Chlorate and Ammonium should never co-exist in the same shell or even in the same workshop. If you use Ammonium Perchlorate (AP) compositions, then you would do best to just avoid chlorates altogether, and vise versa. You can choose the vibrant colors offered by AP or the ease of ignition and brilliant light output offered by chlorates, but don’t be tempted to manufacture both under the same roof and definitely don’t combine both into the same device)
Chlorate and zirconium
Chlorate and red phosphorus
Chlorate and any Sulfur, Sulphate or sulfide compounds
Chlorate and dark aluminum
Chlorate and Antimony Trisulfide (increased friction sensitivity)
Chlorate and Magnesium powder
Chlorate and Titanium (increased friction and impact sensitivity)
Chlorate and any chromium or chromate compound
Chlorate and any metal powders (some already listed)
Chlorate and any metal oxide
Chlorate and lampblack (due to sulfur content)
Chlorate and any hydrocarbon fuel
Chlorate and napthalene
Chlorate and Realgar
Potassium Chlorite impurities in a chlorate compound that exceeds .001%
Potassium Chloride impurities in a chlorate compound that exceeds .08%
Chlorate stars primed with black powder
Chlorate stars in a shell with a burst charge that contains sulfur
Chlorate burst charge in a shell with black powder primed stars
Some chemical combinations might be fine by themselves, but become reactive when a third element such as water, heat or sunlight is introduced during the manufacturing process. The most common reactions are listed below:
Magnesium-Water:this is a very reactive combination that will generate heat to the point of combustion. Compositions containing magnesium powder must never be bound by water. The magnesium must also be coated with a protective barrier even when bound by other solvents such as acetone or NC lacquer. More on this subject can be found here.
Aluminum-Nitrate-water:Any composition containing the commonly used nitrate compounds along with a finely powdered aluminum will be subjected to an accelerated reaction in the presence of water. This reaction will generate heat, which acts as a catalyst to speed the reaction even further, and thus generating even more heat. This heat can easily build up to the point of igniting the composition. The reaction often gives off an odor that can help alert you to the danger. Sometimes the reaction will start to occur during the mixing stage when dampening the composition, since it is in one large clump that traps the heat inside. If you feel the composition gradually warming, spreading it out into a thin layer on a pan will often dissipate enough heat to stop the reaction. The temperature at which the reaction rapidly accelerates is about 176 degrees F. If the temperature of the composition progresses beyond warm during mixing, quickly move it to a safe place outdoors where it can safely ignite without damaging anything.
Aluminum-nitrate reactions can be suppressed with the use of boric acid in order to keep the PH levels around 4.7 to 5.1. The boric acid is often included in the formula for mixtures that are prone to this reaction, but it is more effective if it is dissolved into the water used to wet the composition rather than screening it into the composition itself. Even with the boric acid, aluminum-nitrate stars should always be dried outdoors (in the shade) until you have enough trials to determine if the reaction is prone to occur or not.
Chlorate-tap water:when wetting a chlorate formula with water for binding stars, it is best to use distilled water in order to avoid the presence of iron or calcium carbonate that can sometimes be found in hard tap water. Well water should have a PH close to 7.0 if used.
Chlorate-sunlight:The ultraviolet rays of strong sunlight are capable of decomposing potassium and barium chlorate compounds, which increases their sensitivity. If the composition contains sulfur compounds, any sulfuric acid that forms due to contact with moisture can break the chlorates down into chlorine dioxide, which is decomposed explosively by sunlight. The chlorine dioxide will break down into chlorine and oxygen, which will then ignite any combustible material it contacts.
Most of the hazardous combinations seen above are the result of an increased sensitivity to friction. The amount of energy it takes for any given composition to initiate the decomposition reaction of the oxidizer and the reduction reaction of the fuels is known as the activation energy. Normally we supply all of this energy in the form of heat when we ignite the material with an open flame or spark. However, this energy can be transferred into the material in ways other than heat alone. The two most common alternatives are friction and shock, with friction being the most common problem.
In case you didn’t notice, chlorate is present in every hazardous combination listed above. Chlorate molecules have three loosely bound oxygen atoms that are easily given up during reactions, a process known as decomposition (or “burning” in pyro terms). The fact that the bonds of these oxygen atoms are so easily broken is what accounts for the lower activation energy of chlorate compounds. Perchlorate compounds, by comparison, have four oxygen atoms that are tightly bound, thus it takes more activation energy to start the reaction. This is why perchlorate formulas have a higher ignition point and burn at a slower rate than chlorates.
So not only do chlorate compounds ignite at lower temperatures (which is actually a benefit when you are trying to avoid blind stars), but it also takes less friction to trigger a reaction compared with other oxidizers. Common sources of friction include stars scrapping against each other when loading them tightly into a shell, composition getting pinched between the threads of a lid when screwing the caps on containers, dragging containers and other objects across loose composition that was spilled on a table or floor or scraping a scoop against the bottom of a container when scooping a sensitive composition.
Every composition has an activation point where a given amount of friction will trigger the reaction, regardless of what oxidizer is used. However, this trigger threshold is much higher on some oxidizers than others, such that you would not likely be able to ever generate that much friction with the typical operations being performed. Even something as friction intensive as ball milling is not enough to trigger the threshold for black powder, whereas it would easily set of a chlorate mixture.
Avoiding friction is a good practice regardless of what chemicals you are using. Avoiding compositions that are sensitive to the amounts of friction you are able to produce unintentionally such as by a slipped screwdriver, dropped shell or sliding container is an even better idea.
For chlorate fans who don’t want to give up the bright colors, easy ignition and resistance to blind stars, your formulas can be made less sensitive by following this tip from the Russian chemist A. A. Shidlovskiy: adding non-chlorate oxidizers to any formula containing chlorates will decrease the overall sensitivity of the mixture. This difference can often be dramatic when the chlorate compounds make up less than 50% of the total oxidizer component. If you ever see a chlorate formula that contains other oxidizers and were wondering why they are there, this is the most likely reason. The overall activation energy of the mixture is being raised in order to lessen the sensitivity to friction, while still gaining some of the benefits of using chlorates such as good colors, brighter intensity and lower ignition temperatures.
Shock is another form of mechanical energy input, just like friction, although it is less problematic due to the circumstances required to produce it. Dropping a hammer down on a pile of composition laying on the ground is an example of shock, whereas dragging the hammer across the pile would be friction. About the only common operation that produces shock is hand ramming with a rod and hammer. Once again, chlorates are at the top of the list for shock sensitivity. It goes without saying that chlorate mixtures should never be rammed into a tube or subjected to any similar type of impact. This is a pretty easy one to avoid. You just don’t do it.
Perchlorates can take a lot more shock than chlorate mixtures, but again you may be flirting with that fine line. You may be able to get away with hand ramming a perchlorate mixture 200 times, but that one time it goes on you is all it takes.
Black powder mixtures can be pounded all day long without worry however, which is why they make such ideal rocket fuels. About the only way you could ever reach the activation energy of black powder would be if you managed to create shock, friction and heat all at the same time, such as if a bit of composition sitting on the tip of a bent rocket spindle was pinched between the rammer right at the time of impact. Even this would be a freak accident with a very low probability of occurrence.
Pressing is the safest way to consolidate any pyrotechnic mixture into a tube, since the gradual increase of pressure does not produce any shock forces. Pressing is the only method that should be used for whistle rockets and other perchlorate mixtures that need a strong degree of consolidation. Some mixtures, such as strobe rocket mix, have been known to ignite even when pressed into a tube. Thus care must be taken to know the nature of the formulas you are delaing with before working with them. A polycarbonate blast shield (which won’t shatter like acrylic) should be a fixture on every pressing station, along with the use of safety goggles by the press operator.
Some pyrotechnic mixtures are prone to ignite from static electricity, especially those that contain metallic powders. Even some mixtures that contain no metal at all are still prone to static ignition, such as whistle mix. Flash is one of the more sensitive mixtures, and also the most destructive should even small amounts accidentally ignite.
The best way to eliminate static electricity is with humidity. When the air is humid, water molecules collect on the surface of your skin and other objects, which prevents the buildup of static. The drier your skin is, the easier it will hold a static charge. A good rule of thumb is to stay away from contacting pyrotechnic mixtures when the humidity drops below 50%. You should keep a humidity gauge in your shop for monitoring this percentage. Radio Shack sells such a gauge that reports both humidity and air temperature.
Since cold weather usually brings drier air, humidity levels will be at their lowest during the winter. For Northern states or desert environments, the low humidity in winter months can be a real static risk. Tropical environments like Florida have almost no static problems at all, which may be why several fireworks manufacturers are located there.
There are several precautions that can be taken to minimize the risk in a static prone environment. Many techniques have been developed in the electronics industry to deal with the destructive problems caused by static, and these can be applied to a fireworks shop as well. The trick to getting rid of static is to conduct it away to somewhere else. There is conductive paint that can be used to paint the floor of your shop. A grounded touch pad can be placed at each entry point so that a person can discharge themselves upon entering the work area. Ground straps can also be worn on the wrist, which make a connection from a metal contact point on the wrist strap to a grounded connection on your bench via a long wire. Conductive frocks made from a special material can also be worn to keep charges from building on your clothes.
Using metal scoops also helps eliminate static buildup when transferring mixtures. If you have ever seen red gum align itself in a plastic scoop like steel filings around a magnet, you have seen how easily fine powders can generate a charge on plastic surfaces.
Prepare for the Worst
There are some things in life we don’t like to think about, such as death or sickness, and thus there are things that get put off until late in life like estate planning and wills. In pyro we don’t like to think about major burn trauma or fires, and this can result in diminished efforts in planning for them. By actually having some kind of plan for these situations, the damage done can be greatly reduced. It could even mean the difference between surviving an incident or not.
Escape Route Plan
Wherever you commonly work in your shop, you should have a clear escape route that is free of obstructions like furniture, boxes, equipment etc. If an incident does occur, the chances are very high that you will lose your vision, either from smoke or from temporary blindness caused by a flash of light. Thus you need to have a clear shot to the door that you can make blindfolded without tripping on anything. It would even be a good idea to practice your escape route blindfolded to see how easily you can make it. If an incident occurs, you want your reaction to be automatic. You want to be able to calmly but briskly walk out of your shop without the effects of panic causing you to rush and trip. Once you panic, you are no longer in control and are at the whim of fate.
Burn and Trauma Treatment
A first aid pyro survival kit should include water-gel burn dressings, tourniquets, large gauze rolls and at least one very clean white sheet with which to cover a burn victim, then saturate with water. You should also have a large and ready source of COLD water (and preferably ice) on hand at all times, located where the fire/explosion cannot reach.
Don’t Work Alone
Always have someone within shouting/bell-ringing distance to render aid if you have an accident. Self-treatment of trauma is hard for the untrained individual. You may be too injured or weak to help yourself, anyway. Don’t count on a cell-phone for protection. If you’re missing fingers or are unconscious it will be hard to dial. There needs to be another person – someone NOT at risk in the shop – around for help if you need it.
You should cover as much of your body as possible with 100% cotton when working with energetic materials. Avoid synthetic materials due to the static electricity hazard. Long sleeves and blue jeans might not be comfortable in hot weather, but they’ll save you from burns. The heat from a flash fire is intense but short lived, and even a single layer of cotton cloth can be the difference between a skin graft. Closed-toe hard shoes will protect your feet and allow you to escape over hot or burning debris, where sandals or dress shoes might not.
The precautions listed here are by no means complete, but they represent the most common issues. By adhering to the advice given here, you can at least avoid the bulk of the hazards. It is up to the pyrotechnist to scan books and forums for the advice and experiences of others in a constant search for potential danger.