Bright Star Compositions with High Magnalium Content
From Best of AFN III
In an encyclopedia I found that magnesium powders are used in bright star compositions, but could not find any details concerning components and their respective quantities.
Troy Fish mentions star compositions containing magnalium powders in Pyrotechnica VII.
Today I want to present such a composition that I have used successfully.
The composition is suitable for cut stars, as well as for round stars. For both techniques the composition is wetted using a mixture of equal parts of water and denatured alcohol.
The stars required two layers of prime. After complete drying of the star, the first fire composition is applied and then it is completely dried again. Then the final layer is added.
I have also included an alternate first fire composition from Ellern’s Formula #166. This should be used for fast-ejected stars. The binder is nitrocellulose lacquer. The final layer is the same as mentioned above.
Some modifications are possible. Red gum can be replaced partially or totally with other natural resins like shellac, gum dammar, colophony and Vinsol resin. Shellac also shows the best flame color, but the best ignition is achieved by Red gum. Dammar, colophony and Vinsol show lower burning rates and whiten the flame color.
Strontium carbonate can be replaced by an identical quantity of calcium carbonate. The former yields a vermillion color, the latter is crimson. Instead of strontium carbonate, strontium oxalate can be used, but the color is less intense.
To achieve a satisfactory green star composition, it is necessary to replace strontium carbonate with the same amount of barium carbonate. Barium chromate can be used as well but cannot be recommended because of its toxicity.
For bright yellow stars, I replace 20% strontium carbonate with 12% of ultramarine blue. For orange colored stars, mixtures of both are suitable.
To improve ignition and burning rate of the stars, it is possible to add red iron oxide, black iron oxide or cupric oxide in concentrations of about 2%. Both iron oxides whiten the flame color slightly, cupric oxide gives the stars a bluish tint. The addition of potassium dichromate in concentrations of 2-4% apparently improves combustibility, but cannot be recommended because of the enormous toxicity and carcinogenicity.
For extremely hard stars, the dextrin content can be increased or may be substituted by glutinous rice starch.
|Magnalium, -80/-100 mesh||30|
|Iron oxide, black||1|
(bind with N/C lacquer)