Part VII. On Composition Series for Practical Use
ABSTRACT:
(1) The spectroscopic studies in the previous Parts are summarized so as to apply the principle of flame color creation for practical use.
(2) According to the results of (1), various samples of red, yellow, green and blue of several composition series are prepared. Their flame colors are examined by the naked eye and good colors are selected. According to these, effective color zones are written as enclosed areas in triangle graphs.
(3) As far as these studies are concerned the important results that seem to be common for each series are as follows:
a) The width of an effective composition zone in a graph is very narrow for low temperature flames and fairly wide for high temperature flames.
b) Ammonium perchlorate is the best oxidizer, for it can produce HCl in a flame and creates deep color.
c) Polyvinyl chloride is also the best additional ingredient that can create a deep color by producing HCl gas in the flame like ammonium perchlorate. d) It is necessary to completely protect compositions from moisture for high temperature flames to prevent the magnesium and other ingredients from reacting with each other. For practical applications deep and brilliant color flames are obtained only in accord with this consideration.
Ref: Selected Pyrotechnic Publication of Dr. Takeo Shimizu, Part 3, pp 107-119
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Part VI. Flame Spectra of Metal Aluminum Compositione
ABSTRACT: The previous Parts showed the effect of magnesium powder as a fuel in high temperature compositions. In this Part the effect of aluminum powder is examined. In general aluminum melts and is sprayed as sparks out of the flame. It is not as easily vaporized because of its high boiling point. With aluminum the intensity of the spectrum of color-producing bands is not as high as with magnesium.
Ref: Selected Pyrotechnic Publication of Dr. Takeo Shimizu, Part 3, pp 103-105
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Part V: Flame Spectra of Blue Color Compositions
ABSTRACT: We can see three different flame colors (i.e., blue, light green and reddish orange) when we insert a small copper piece into a flame of a burner. The blue color is caused by CuCl bands with the strongest lines between 4269–4560 Å. Our goal is to use this color for fireworks. Blue is produced by some copper salts or copper metal powder in the presence of chlorine or hydrogen chloride gas, but if the concentration of gas is small, the blue color is interfered with by the light green color, which seems to be caused by a continuous spectrum of other copper chloride bands (5263–5531 Å).
The flame spectra are examined under various conditions. For low temperature flames, ammonium perchlorate is the best oxidizer and produces an excellent bright blue. For high temperature flames it is necessary to decrease the percentage of magnesium powder, because the CuCl bands seem to dissociate with increasing magnesium.
Ref: Selected Pyrotechnic Publication of Dr. Takeo Shimizu, Part 3, pp 87-102
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Part IV. Flame Spectra of Red, Yellow and Green Color Compositions
ABSTRACT: lame spectra of red, yellow and green color compositions are examined under various conditions.
a. Red Flame
A red flame is produced by bands from strontium (Sr) salts. These bands consist of five main bands [i.e., (6013), (6203), (6300), (6428) and (6558)], where each number represents the wavelength of the maximum intensity in Angstroms (Å). The influence of chlorine on the band is quite different from theothers, namely the band is weakened by chlorine, whereas chlorine intensified the others, and this effect is greater with hydrogen chloride gas than with chlorine gas. This is very clearly observed especially in low temperature flames. The influence of strontium salts is very small. The effect of oxidizers that produce either chlorine or hydrogen chloride gas is quite remarkable. If we add ingredients that have chlorine, they can intensify each band only in high temperature flames. The effects of calcium (Ca) salts were also examined.
b. Yellow Flame
A yellow flame is produced by sodium (Na) salts. The spectrum consists of mainly Na-D lines, but in addition, a continuous spectrum from Na atoms appears between 5,800 and 6,100 Å and makes the flame color rather white, especially at high flame temperatures.
c. Green Flame
Only BaCl bands can produce green flames when barium (Ba) salts are used as the color agents. Compositions without chlorine cannot produce green color because only BaO bands appear, giving white color to the flames. In the presence of chlorine both BaCl and BaO bands appear. The effect of chlorine or hydrogen chloride gas in a flame seem to weaken the BaO bands and to intensify the BaCl bands. The effect of chlorine gas is less than that of hydrogen chloride gas. And so, ammonium perchlorate produces a better green color than potassium perchlorate. Adding some kind of chlorine compound (chlorine donor) is also effective to intensify the green color.
Ref: Selected Pyrotechnic Publication of Dr. Takeo Shimizu, Part 3, pp 57-86
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Part III. On Backgrounds of Color Flame Spectra
ABSTRACT: Blank runs were made with nominal colorproducing compositions to investigate the lines, bands or continuous spectra that appear as background and interfere with the desired spectra of red, yellow, green, etc. These sample compositions consisted of solid materials such as oxidizers (ammonium perchlorate, potassium chlorate, potassium perchlorate, potassium nitrate, etc.), low temperature fuels (shellac, rosin, pine root pitch, etc.), and magnesium powder for the high temperature fuel.
For low flame temperatures sodium D (Na-D) lines (5890 and 5896 Å, caused by impurities contained mainly in the oxidizers), continuous spectra (caused by carbon particles and potassium atoms) and potassium (K) lines (5802, 5783, 5832, 5813; 5340, 5324, 5360, 5343; 5090, 5084, 5113, 5080; 4044, 4048 Å) are observed. For high flame temperatures Na-D lines are also observed, and in addition to the above, MgO bands and continuous spectra (the latter are caused by solid metal oxide particles and K atoms) are found.
The main interfering spectra are the Na-D lines and continuous spectra. Purification of ingredients is very important to remove Na-D lines and to obtain fine colored flames. For high flame temperatures, the addition of chlorine- containing compounds such as polyvinyl chloride, ammonium chloride, etc. to a composition is effective in decreasing the intensity of the continuous spectra, and it is assumed that the metal oxide of the solid phase is converted into the metal chloride of the vapor phase in the presence of chlorine or hydrogen chloride in the flame, but this should be ascertained by further experiments of higher accuracy. The addition of shellac is also effective in weakening the intensity of the continuous spectra and decreasing the black body temperature of the flame.
The permeability coefficients and black body temperature of flames of basic compositions are measured for reference .
Ref: Selected Pyrotechnic Publication of Dr. Takeo Shimizu, Part 3, pp 39-56
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Part II. Temperature Measurement of Flames by Means of the Line-Reversal Method
ABSTRACT: Using the theory developed in Part I, flame temperatures for various fireworks compositions have been measured by means of line-reversal of the Na-D lines. (1) For low flame temperature compositions: Compositions that contain combustible organic materials (i.e., shellac, rosin, pine root pitch, etc.) are commonly used in ordinary fireworks. The author prepared various combinations of components to see the influence of oxidizers, fuels, color agents, etc. Temperatures are measured by method 1 from Part I. The result shows that the highest temperature appears at the base of the flame. Generally potassium perchlorate gives higher temperatures than ammonium perchlorate. Potassium nitrate always gives lower temperatures than other oxidizers.
Ref: Selected Pyrotechnic Publication of Dr. Takeo Shimizu, Part 3, pp 15-37
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