Green flame compositions

Red signal flare Unpublished (very little residue) 

An oxygen-deficient flame is required for a good quality green flame. Otherwise, barium oxide (BaO) will form and emit a series of bands in the480- to 600-nanometer range, yielding a duU, yellowish green color. The reaction 

This tanperatuie dependence and the value of a chlorine source are important to remanber. A binary mixture of barium nitrate and magnesium or magnalium metal 

TABLE 8.12 Green Flame Compositions Composition % by Weight 

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Barium nitrate is a white, crystalline, non-hygroscopic material with a melting point of approximately 592°C. It is commonly used as the principal oxidizer in green flame compositions, gold sparklers, and in photoflash mixtures in combination with potassium pert hlorate. ... 

In practice, both red and green star compositions are formulated to have a negative oxygen balance i.e. there is an oxygen deficiency) since the presence of a reducing atmosphere in the flame inhibits the oxidation of MCI to MO (where M is Sr or Ba), thus enhancing the colour purity of the flame. 

The diagram is quite convenient for designing colour flame compositions. For example, when a red colour represented by Pi is mixed with a green the new colour moves along the straight line P -Pilike P The coordinates have the following relations ... 

The BOjj, spectrum for a green flame might be suggested using boric acid as a colour producing agent, but it is too weak to use practically in firework compositions. 

Barium carbonate gives a pretty green flame in a composition which contains ammonium perchlorate as the oxidizer, and the colour is better than that produced by using barium nitrate. 

Potassium emits weak violet light (near 450 nanometers), but good red and green flames can be produced with potassium compounds present in the mixture. Ammonium perchlorate is advantageous for color compositions because it contains no metal ion... 

Elemental composition Pt 73.36%, Cl 26.64%. The compound is dissolved in concentrated HCl, diluted, and analyzed for platinum by flame-AA spectrophotometry (see Platinum). The salt may be identified by its ohve green color and other physical and x-ray properties. It forms a dark brown color in HCl. 

To use potassium nitrate in colored flame mixtures, it is necessary to include magnesium as a fuel to raise the flame temperature. A source of chlorine is also needed for formation of volatile BaCl (green), or SrCl (red) emitters. The presence of chlorine in the flame also aids by hindering the formation of magnesium oxide and strontium or barium oxide, all of which will hurt the color quality. Shidlovskiy suggests a minimum of 15% chlorine donor in a color composition when magnesinm metal is nsed as a fuel [5]. 

Pyrotechnic compositions containing a barium compound and a good chlorine source can generate barium monochloride, BaCl, in the flame and the emission of green light will be observed. BaCl - an unstable species at room temperature - is an excellent emitter in... 

Green J (1989) Flame retardants and smoke suppressants. In Katz HS, MUewski JV (eds) Handbook of fiUers for plastics. Van Nostrand, New York, chapter 4, p93 Hornsby PR, Watson CL (1986) Plast Rubber Process Appl 6 169 Rothon RN (1995) Effects of particulate fiUers on flame retardant properties of polymers. In Rothon RN (ed) Particulate-fiUed polymer composites. Longman, Harlow, Chap 6,p207... 

Copper-I-chloride forms a white crystalline powder, which is stable in dry air, but tends to turn yellow, green, blue, or brown on exposure to moisture, air, and light. Store dry in airtight amber glass bottles. The dry crystals have a melting point of 430 Celsius. The crystals are relatively insoluble in water, with partial decomposition, but are soluble in concentrated hydrochloric acid, and ammonia solutions. Copper-I-chloride can be used in pyrotechnic compositions, for imparting cool effects to the flames. Copper-I-chloride is a very useful catalyst for use in chemistiy. 

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