SENKO HANABI - Safety

SAFETY

The text font speaks for itself. Safety must always be the greatest concern on your mind. Here are some imperative safety measures to be incorporated in your fabrication process.

This is the first chapter that I put on this website. And not without reason. However small these little pyrotechnic devices may be, they still rely on a very exothermix (heat generating) reaction that can cause serious burns. The Senko Hanabi composition is in fact nothing more (nor less!) than a modification of black powder. Therefore it is capable of explosive reactions when confined. If unconfined, a small or even a large sample will burn away with constant speed. However, the speed of burning increases with an increase in the surrounding pressure. The net result when the mixture burns in a confined space is therefore an exponential rise in pressure and burning speed, causing an explosion. This may occur for example when mixing the ingredients, during manipulation of containers or during storage. So
Senko Hanabi is not as innocent as it seems.
However, for the responsible individual, the use of common sense and a notion of the following precautions will be enough to safely engage in the challenging and very rewarding construction of these delicate sparklers:

1) Consider the worst-case scenario:

What if the composition you are handling right now catches fire? Would it be likely to explode? Would it set fire to a nearby composition or to finished devices? Would it be able to burn your hands or your face? Would it set fire to your clothing or surroundings? What if it does? Do you have the means to extinguish a beginning fire? Personally, I always work with a small fire-extinguisher near me. You can by one quite cheaply at a car-part shop. A bucket of water to cool your burned hands can be just as helpful in extinguishing a beginning fire (although quite messy). These questions should always be in the back of your head. All the following safety measures merely decrease the incidence of this worst-case scenario.

2) Keep your working place tidy:

This is a very important point in pyrotechnics. Many compositions are very sensitive to friction or impact. This means that collections of dust of these mixtures may ignite unexpectedly when accidentally struck. Although nitrate-based compositions are not very sensitive, the presence of sulfur facilitates ignition. Apart from catching fire, loose composition is more likely to get accidentally swallowed. The working area should be wiped up and sponged down after each operation.

3) Be careful with irritating or harmful ingredients:

Since we are dealing with chemicals, we should be aware of the consequences of their accidental ingestion or inhalation. Luckily, unlike some other pyrotechnic chemicals (e.g. Barium-salts), the substances involved in making Senko Hanabi are not very toxic. One very important exception is realgar (Arsenic sulfide) which is called for in a formula taken from Shimizu. I myself have not yet tried this formula, because then I would have to worry about its toxicity from the moment I opened the bottle to the moment I had to dispose of the toxic remains of a burned Senko Hanabi. Not to mention the smoke while burning. You can of course choose to try this formula, but be aware of its toxic nature. Much less toxic, even so little that it is only called 'harmful', is potassium nitrate, the main oxidiser in the initial burning reaction. The dose one has to swallow or inhale to reach toxic limits is very unlikely to be reached only by accident. Nonetheless, eating or drinking while manufucturing Senko Hanabi is always a bad idea. If you spill any composition or ingredients, clean up immediately. Mind you that potassium nitrate and other products are irritating to the eyes, skin and lungs.

4) Keep ignition sources well away:

For obvious reasons. These include smoking, a hot stove, a hot lamp, ashtrays, candles, incense, ...

For even more obvious reasons, you could as well quit smoking altogether.

5) Prevent static discharge:
Perhaps the leading cause of accidents in the manufacturing of pyrotechnics. Not easy to eliminate, but the following tips should keep you safe:
*wear cotton clothing. Tempting as it may be (in winter), do not wear synthetic (e.g. fleece) clothing. They tend to build up static electricity very quickly. Cotton does not present this problem. Secondly, in case of some burning composition landing on you, cotton will not melt over and into your skin.
*Do not work in a very dry environment. This is often the case in winter. Sparks are much more likely to travel through dry air than through humid air. A rule of thumb is a relative humidity of more than 70%.
*Ground yourself before touching any composition/spoon by simply touching your working surface. This will already discharge you before a spark can travel to the composition.

6) Don't use sparking tools:
Iron, steel and galvanized steel can all strike sparks and cause fires. As far as feasable, use tools made of wood, aluminium, brass or plastic (although the latter may cause static buildup).

7) Don't store Senko Hanabi composition in glass jars or metal containers:
These will cause dangerous shrapnel in case of an explosion. It is important to use cardboard or light plastic containers, such as film cans or ziploc bags.

8) Wear personal protection:
Use eye protection. Normal glasses are not adequate. Contact lenses are worse than nothing. A pyrotechnician should purchase and use safety glasses with side shields, or a face shield. I myself have constructed one from a builder's helmet and a piece of PVC-plate. Wearing heat-resistant gloves might prove impossible in the senko hanabi manufacture, as you will experience yourself.

9) Small is beautiful:
In Senko Hanabi, as you will discover, it is even necessary to keep your droplet small. Nonetheless, even if it were possible to keep a large ball of fire hanging in the air, one still had to consider following facts: mixing large amounts of composition will result in a larger explosion if one should occur. Storing large amounts will present the same problem. Having a large open container of composition in your working area is asking for trouble.

10) Stay green:
Being overly familiar with certain things tends to make one lower one's guard and assume that nothing can go wrong. There are too many variables to make this assumption. Nonetheless, this is the main reason why experienced people have accidents. The right combination of changes can be just enough to make something unexpected happen. Stay alert. Stay green.