[Previous Section] [Table of Contents][Next Section] ------------------------------------------------------------------------ ------------------------------------------------------------------------ Chapter Seventeen: The Chemistry of Pyrotechnics Most pyrotechnic mixtures follow a very simple set of chemical rules. We'll go over those now. Most mixtures contain an oxidizing agent, which usually produces oxygen used to burn the mixture, and a reducing agent, which burns to produce hot gasses. In addition, there can be coloring agents to impart a color to the fire, binders, which hold the mixture in a solid lump, and regulators that speed up or slow down the speed at which the mixture burns. These are not all the possibilities, but they cover most all cases. Oxidizing agents, such as nitrates, chlorates, and perchlorates provide the oxygen. They usually consist of a metal ion and the actual oxidizing radical. For example, Potassium Nitrate contains a metal ion (Potassium) and the oxidizing radical (the Nitrate). Instead of potassium, we could instead substitute other metals, like sodium, barium, or strontium, and the chemical would still supply oxygen to the burning mixture. But some are less desirable. Sodium Nitrate, for example, will absorb moisture out of the air, and this will make it harder to control the speed at which the mixture will burn. In the following examples, we'll use the letter "X" to show the presence of a generic metal ion. Note that Nitrates are stingy with the oxygen that they give up. They only give one third of what they have. Some Some Nitrate Nitrite Oxygen 2XNO ---> 2XN0 + O 3 2 2 Chlorates are very generous, on the other hand. They give up all the oxygen they have. Furthermore, they give it up more easily. It takes less heat, or less shock to get that oxygen loose. Mixtures using chlorates burn more spectacularly, because a smaller volume of the mix needs to be wasted on the oxidizer, and the ease with which the oxygen is supplied makes it burn faster. But the mixture is also MUCH more sensitive to shock. Some Some Chlorate Chloride Oxygen 2XClO ---> 2XCl + 3O 3 2 Perchlorates round out our usual set of oxidizing tools. Perchlorates contain even more oxygen than Chlorates, and also give it all up. However, they are not as sensitive as the Chlorates, so they make mixtures that are "safer". That is, they're less likely to explode if you drop or strike them. Some Some Perchlorate Chloride Oxygen XClO ---> XCl + 2O 4 2 Reducing agents, like sulfur and charcoal (carbon) simply burn the oxygen to produce sulfur dioxide and carbon dioxide. It's usually best to include a mixture of the two in a pyrotechnic mixture, as they burn at different speeds and temperatures, and the proper combination will help control the speed of combustion. Also, when extra fast burning speed is needed, like in rockets and firecrackers, metal powder is often added. The finer the powder, the faster the burning rate. The proportions change the speed, as well. Magnesium powder or dust is often used for speed. Aluminum dust works, but not as well. Zinc dust is used in some cases. Powdered metal, (not dust) particularly aluminum or iron, are often used to produce a mixture that shoots out sparks as it burns. In rare cases, it is desirable to slow down the burning speed. In this case, corn meal is often used. It burns, so acts as a reducing agent, but it doesn't burn very well. Coloring agents are very interesting. It's long been known that various metals produce different colored flames when burned in a fire. The reasons are buried in the realm of quantum physics, but the results are what matters, and we can present them here. Note that if we use an oxidizing agent that contains a colorizing metal, it can do a double job. It can produce oxygen and color. Barium: Barium salts give a pleasant green color. Barium Nitrate is most often used. Strontium: Strontium salts give a strong red color. Strontium Nitrate is a very convenient material for red. Sodium: Sodium salts give an intense yellow color. So intense in fact that any sodium compounds in a mixture will usually wash out other colorizers. As has been said, Sodium Nitrate absorbs moisture from the air, and so is not really suitable to impart color. Instead, Sodium Oxalate is usually used. This does not absorb lots of water, but has the disadvantage of being very poisonous. Copper: Copper salts are used to give a blue color. Blue is the most difficult color to produce, and it's usually not too spectacular. Usually Copper Acetoarsenite (Paris Green) is used. This compound contains arsenic, and is very poisonous. Since it still doesn't produce a very memorable blue, it's often used with mercurous chloride, which enhances the color, but is also poisonous, and expensive, to boot. Potassium: Potassium salts will give a delicate purple color, if they're very pure. The cheaper lab grades of potassium nitrate often contain traces of sodium, which completely obscure the purple color. In order to get the purple coloring, very pure grades must be used, and you must be very careful to mix it in very clean vessels, and scoop it from the supply jar with a very clean scoop. The color is certainly worth the effort, if you can get it. Some mixtures that burn in colors also contain binders, that hold the mixture together in a solid lump. These lumps are usually referred to as stars. The balls fired from a roman candle or the colorful showers sprayed from aerial bombs are examples of stars. Depending on the mixture, the binder is either a starch called dextrin or finely powdered orange shellac. A shellac-like material called red gum is also used on occasion. In some mixtures, the shellac powder also helps produce a nice color. Shellac mixtures are moistened with alcohol to get them to stick together. Dextrin mixtures are moistened with water. If the colored mixture is to be used as a flare, it's just packed into a thin paper tube. If it's to be fired from a roman candle, it's usually extruded from a heavy tube by pushing it out with a dowel, and the pieces are cut off as the proper length pops out. Stars fired from an aerial bomb are usually made by rolling the moist mixture flat, and cutting it with a knife into small cubes. Stars that are extruded are often called "pumped stars" those that are rolled out are "cut stars". The following are formulas for mixtures that burn with various colors. Parts are by weight. Red Potassium Chlorate 9 Sulfur 2 Lampblack 1 Strontium Nitrate 9 bind with shellac dissolved in alcohol Blue Potassium Chlorate 9 This one is inferior Copper Acetoarsenite 2 Potassium Chlorate 12 Mercurous Chloride 1 Copper Sulfate 6 Sulfur 2 Lead Chloride 1 bind with dextrin Sulfur 4 in water bind with dextrin in water Green Barium Chlorate 8 Barium Nitrate 3 Lampblack 1 Potassium Chlorate 4 Shellac Powder 1 Shellac Powder 1 bind with alcohol Dextrin 1/4 Bind with alcohol Yellow Potassium Chlorate 8 Potassium Chlorate 8 Sodium Oxalate 3 Sodium Oxalate 4 Lampblack 2 Shellac Powder 2 Bind with shellac in Dextrin 1 alcohol or dextrin Bind with alcohol in water White Potassium Nitrate 6 Sulfur 1 Antimony Sulfide 2 bind with dextrin in water Orange Strontium Nitrate 36 Sodium Oxalate 8 Potassium Chlorate 5 Shellac Powder 5 Sulfur 3 Bind with alcohol Purple (ingredients must be very pure) Potassium Chlorate 36 This one has more of a lilac color Strontium Sulfate 10 Potassium Chlorate 38 Copper Sulfate 5 Strontium Carbonate 18 Lead Chloride 2 Copper Chloride 4 Charcoal 2 Lead Chloride 2 Sulfur 12 Sulfur 14 Bind with dextrin in Bind with dextrin in water water Brilliant White Potassium Perchlorate 12 Aluminum Dust 4 Dextrin 1 Bind with water Golden Twinkler Stars Falls through the air and burns in an on and off manner. The effect is spectacular. A pumped or cut star. Potassium Nitrate 18 Sulfur 3 Lampblack 3 Aluminum Powder 3 Antimony Sulfide 3 Sodium Oxalate 4 Dextrin 2 Bind with water Zinc Spreader Stars Shoot out pieces of burning zinc and charcoal.These stars are much heavier than usual, and require larger charges if they're to be fired from a tube. Zinc Dust 72 Potassium Chlorate 15 Potassium Dichromate 12 Granular Charcoal 12 Dextrin 2 bind with water Electric Stars Stars that contain aluminum powder Potassium Nitrate 15 Potassium Chlorate 60 Aluminum, fine 2 Barium Nitrate 5 Aluminum, medium 1 Aluminum, fine 9 Black Powder 2 Aluminum, medium 4 Antimony Sulfide 3 Aluminum, coarse 3 Sulfur 4 Charcoal 2 bind with dextrin in Dextrin 5 water bind with red gum in water Potassium Perchlorate 6 Barium Nitrate 1 Potassium Perchlorate 4 Aluminum 20 Aluminum, medium 2 Dextrin 1 Dextrin 1 bind with shellac in bind with shellac in alcohol alcohol Simpler Zinc Spreaders Potassium Nitrate 14 Potassium Chlorate 5 Zinc Dust 40 Potassium Dichromate 4 Charcoal 7 Charcoal, medium 4 Sulfur 4 Zinc Dust 24 bind with dextrin in bind with dextrin in water water Willow Tree Stars Use large amounts of lampblack -- too much to burn fully. Gives a willow tree effect. Potassium Chlorate 10 Potassium Nitrate 5 Sulfur 1 Lampblack 18 bind with dextrin in water As always, don't forget that it's just plain stupid to go buying all these materials from one chemical supply house. When you buy it all as a group, they know what you plan to do with it, and they keep records. If anyone goes investigating the source of homemade fireworks and checks with your supplier, there will be a lead straight to you. Be sure to cover your tracks ------------------------------------------------------------------------ [Image] Back to Dark [Goto the Top55 HPAVCW Sites!] Secrets of the Underground [Top100 Hacking Sites!!]