Bengal fires are a mixture of oxidizing and reducing chemicals (fuel + oxidizer) and flame coloring agents. The dyeing flame used cations of Na, K, Li, CuCl, etc. As an oxidizing agent used potassium chlorate, potassium nitrate, potassium perchlorate, etc. The fuel used various inorganic and organic substances: sucrose (sugar), charcoal, shellac, sulfur, etc. To increase the intensity used powdered metals such as Mg, Al, Zn, Cu, Ce, Ti, etc.
Potassium dyed purple flame while, but with a relatively low intensity, it very easily "drown out" the majority of other ions. To prepare the violet flame is therefore not well suited potassium. His intensity is so "weak" that it can be used in pyrotechnics coloring flame red, yellow, orange, less often green. A typical example is the notional composition comprising potassium nitrate, strontium nitrate, shellac. Potassium nitrate here acts as an oxidizing agent, reducing the amount of Sr (NO3) 2 (and thus cheaper composition, in most cases it is sufficient content of the flame coloring component in the mixture around 30-70%) and does not diminish the resultant red color.
Strontium dyed bright red flame, apply what has been said (not to be combined with sodium cations or red color turns into an orange, which, as well as other combinations of ions is used to achieve the "exotic" colors). Most are used strontium nitrate, less chlorate, strontium carbonates, oxalates, chlorides.
Barium dyed green flame, but can easily deteriorate by the presence of sodium ions. This must be careful, otherwise arise ugly greenish, very distinctive color. Similarly, plain color arises even when using powders containing sodium (eg Ba (NO3) 2, shellac, sulfur). This is due to lower intensity of green color (slightly dissociated ions about also below), which can be made more effective by adding anions, which increase the volatility (halogen)
Lithium provides the red color and the like in the case of Ba2 + is suitable to add the mixture of volatile halogenated (chlorides), which increases its purity. Lithium is a cheap substitute for strontium ions, particularly as nitrate, lithium, whose price is now around 200 CZK / kg, while strontium nitrate is about 500-900 CZK / kg.
Calcium dyed orange flame, caught on the designation brick-red to brick-orange color. In the mixture (compared to pure compound of calcium) will see more orange to orange-yellow. The purity of orange us is complicated by other ions (again most ubiquitous sodium), so do not expect composition KNO3/CaC2O4/palivo be stained orange flame. If we want to achieve a beautiful orange color is preferred to use a combination of Ca2 + / Sr2 +. A mixture of calcium and sodium cations gives a golden color.
These bengal fires take color from red through purple to pink