INGREDIENTS & MATERIALS


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This section discusses the natural and chemical ingredients one needs in order to compose Senko Hanabi formulations. Secondly, it will cover the necessary materials and tools to safely make the composition into a beautiful sparkler.


INGREDIENTS MATERIALS
  1. Potassium Nitrate

  2. Charcoal

  3. Sulfur

  4. Paper

  5. Soot
  1. SAFETY EQUIPMENT & CLOTHING
    Mandatory!

  2. Working Surface


  3. Milligram Scale








INGREDIENTS:

The basic Senko Hanabi composition is a well-balanced mixture of potassium nitrate, sulfur and a carbon-source. However, other constituents can have an influence on the overall effect as well. At the moment, I have not yet done much experimentation in this field. Nonetheless, I will provide the information I have gathered and learned until now:

1) Potassium nitrate:
This is the chemical name for a substance commonly known as saltpetre. It has many uses in industry and agriculture. Thus it is supplied in many different forms and purity specifications:
-Laboratory grade: very pure and expensive: probably wasted in Senko Hanabi.
-Pharmacy grade: a good choice, considering the proximity of a pharmacy and the small amounts of pyrotechnic composition needed. Might turn out expensive.
-Technical grade: good enough (>98,5% pure) and affordable. One usually buys this grade in 1kg amounts. Not every drugstore or hardware-store sells it though. Keep on asking.
-Fertilizer grade: generally, this grade contains more impurities than the other ones. In a carefully balanced composition, these could prove to deteriorate the effect. Also, the exact chemical analysis is not always easy to decipher.

Potassium nitrate is the main constituent of any senko hanabi formulation. Its function is twofold: it carries the oxygen molecules needed in the complex oxidation processes and ends up as the reagent potassium polysulfide in the second reaction. It has been in use since antiquity. The granular material often cakes into hard non-friable lumps. This makes it somewhat hard to use in its raw form. Therefore, ball milling or precipitating the potassium nitrate is necessary to obtain a very fine powder that is easily and consistently mixed with the other ingredients. These techniques will be explained in a later chapter.

 2) Sulfur:
Just as potassium nitrate, sulfur comes in a variety of grades and forms: there is agricultural grade, flowers of sulfur, sulfur flour,... It's not always quite clear what the distinctions are between them. As for Senko Hanabi, because we only need small quantities, it might be a good idea to settle with the pharmacy grade. This is a very fine, yellow-fluorescent powder, made by sublimating impure sources of sulfur. After condensation, the traces of acid are washed out of the crystals ("flowers of sulfur"). The result is a very fine, very pure, ready to use form of sulfur. It has the following functions (or drawbacks) in a senko hanabi formula: -it serves as a fuel for the initial redox-reaction and ends up in potassium sulfate or potassium (poly)sulfide -it lowers the ignition temperature of the pyrotechnic composition: above 180°C, the S8-molecules begin to decompose and form highly reactive S2 and S3 fragments. These attack the surface of the oxidizer particles, generating heat that will cause more S8-ringmolecules to break down into fragments and so on.... -it increases the sensitivity to impact: the S8-rings can also be broken into fragments by friction or impact. Black powder is ignited when a weight of 2kg falls on it from a height of 70cm. This distance decreases with every increase in sulfur content, so beware with these sulfur rich senko hanabi-compositions. -from my own experimentation, it seems that it helps in starting the second reaction as well (see theory). Sulfur-rich mixtures very easily and quickly form a boiling droplet.


3) Carbon-source:
*Charcoal:
Charcoal varies tremendously depending on the wood source and the method of manufacture. It is not at all pure C12. Instead, it is a complex mixture of substances. For example: a 'highly carbonized' sample of charcoal could be represented by C20H7O (Shimizu). The various grades and types of charcoal give very different properties in pyrotechnic formulations. In traditional Senko Hanabi recipes, it is often Pine charcoal or Paulownia charcoal that is called for:
-Pine charcoal: produced by carbonization of pine-wood on a heat source. I make mine by 'baking' a cookie-can (with a little opening in the lid) stuffed with pine-wood from the department store on a hot charcoal barbecue. Yep, that's right: making charcoal by burning charcoal. First, if your wood was wet, you evacuate the steam. Then it starts to smell really smokey, and after a while you can ignite the volatiles that are driven out of the wood through the opnening in the lid. Eventually, when the flame dies out, I can see through the little opening that the charcoal inside is glowing red. I assume this means that I have a highly carbonized (read volatile-poor) type of charcoal. Pine is easy to find, cheap, and the sparks that the charcoal generates in a boiling senko hanabi-droplet are very beautiful and intense: the first sparks shoot out to approximately 10-15cm. They are like a miniature shell shot out of the ball. You can see a single line, which at the end explodes in a small and dense bush of sparks. Then, when the ball shrinks, the sparks become more numerous but get shorter and branch less.
-Paulownia charcoal: I went through a great deal of phoning and net-surfing before I finally found a source of Paulownia-wood in my neighbourhood. Eventually, I helped in cutting branches from young trees in a nursery. The trees themselves give very fragrant blue flowers before they get leaves. The leaves themselves can measure up to 50cm! Also, the branches are hollow ans easily decorticated when fresh. I processed them just in the same way as the pine charcoal, but the effects were somewhat disappointing. It's true that paulownia charcoal produces branching sparks in senko hanabi, but I found these a lot less attractive or impressing then the ones from pine charcoal. Perhaps it has got something to do with the age of the wood, or my processing technique, but to be honest, I doubt it will ever surpass pine charcoal (especially taking into account the work one has to put into obtaining this not so common wood).
-Kleenex+sugar charcoal: this is where it all started for me. After reading about senko hanabi on Alan Yates' website, I browsed through the rec.pyrotechnics discussion group. There I found an article written by ....... . In it, he explains the manufacture of very rudimental senko hanabi. He also tried to standardise the carbon-source. He proposed doing this by carbonizing Kleenex-tissue paper soaked in a sugar-solution. I started out just as he said, and after some trying with different paper-sources and wrapping techniques, I witnessed my first senko hanabi-sparks! Thank you very much for this, but to be honest, when one has seen the sparks given off by pine charcoal (also easily obtained, more or less standard), one will not make the sweet-paper-charcoal twice.
-other charcoal-sources....: to be continued, feel free to experiment and share your experiences!

*Soot:
In Senko Hanabi, this is the caviar. Not only is the amateur manufacturing of soot a very challenging task (making it even much more expensive than caviar!), the sparks that shoot from a soot-droplet are by far the longest and the most 'flowery'. However, just as for charcoal, the source and way of processing determine the different effects.
-butane soot: the byproduct of a badly tuned gas-burner. You can scrape it off the pot that's on the stove. I myself have collected soot from an afternoon of beer-making (yes, there's more to life than senko hanabi!). At first, it didn't do a thing as spark-source, but when I put it in series with an already started droplet, it started to give off the soot-specific(?) sparks. These are much like the pine-charcoal bushy explosions. The difference is that the pattern is more sparse but of a larger diameter, more flowery. Also, the little explosions are not as loud. Perhaps I will try to tune this type of easy soot one day...
-pine soot: after the somewhat disappointing results of the paulownia charcoal, I managed to make some pine-soot from burning pine-resin scraped off some trees. I was thrilled with the results. This is just beautiful! Sparks of up to 30cm (more than fifty times the diameter of the droplet!), delicately branching, exploding into chrysanthemum-flowers the size of oranges!
-other types of soot...: please experiment and share your observations!


4) Alternative sulfur-sources:
*Realgar: