Photoflash Mixtures

To produce a burst of light of short duration, a composition is required that will react very rapidly. Fine particle sizes are used for the oxidizer and fuel to increase reactivity, but sensitivity is also enhanced at the same time. Therefore, these mixtures are quite hazardous to prepare, and mixing operations should always be carried out remotely. Several representative photoflash mixtures are given in Table 8.3. 

Flash powders are among the most energetic, sensitive, and explosive of all pyrotechnic compositions. There is sometimes debate and friendly discussion about whether or not very reactive flash powders function by a deflagration or detonation mechanism. It is trnly an academic argument—there is no question that they can explode violently, whatever the reaction process is. 

The production of brilliant sparks is one of the principal effects available to the fireworks manufactnrer and to the special effects indnstry. Sparks occur during the bnm-ing of many pyrotechnic compositions, and they may or may not be a desired feature. 

Barium nitrate, BafNOjlj 50 Gold sparks (sparkler) 7 

Potassium perchlorate, KCIO4 50 White sparks waterfalls 7 

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Because of its higher melting point and less-exothermic decomposition, potassium perchlorate produces mixtures that are less sensitive to heat, friction, and impact than those made withKClO] [2]. Potassium perchlorate can be used to produce colored flames (such as red when combined with strontium nitrate), noise (with aluminum, in "flash and sound" mixtures), and light (in photoflash mixtures with magnesium). 

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. ... 

Therefore, the initial choice for an oxidizer is one with an exothermic heat of decomposition such as potassium chlorate (KCIO 3). However, mixtures of both chlorate and perchlorate salts with active metal fuels are too ignition-sensitive for commercial use, and the less-reactive - but safer - nitrate compormds are usually selected. Potassium perchlorate is used with aluminum and magnesium in some "photoflash" mixtures these are extremely reactive compositions, with velocities in the explosive range. 

Photoflash" mixtures, 145-148 Photon, energy of, 46 Potassium chlorate acid with, 57 discovery of, 4 hazards of, 59, 109, 134 in colored flame mixtures, 156, 161... 

An intimate mixture of the finely divided components, once widely used as a photoflash composition, is readily ignitable and extremely sensitive to friction or impact. 

SAFETY PROFILE A poison by ingestion, subcutaneous, parenteral, and intravenous routes. An irritant to skin and eyes. When heated to decomposition it emits vety toxic fumes of NO. An oxidizer. Mixtures with finely divided aluminum-magnesium alloys are easily ignitable and extremely sensitive to friction or impact. Such mixtures are used in chemical photoflash applications. Incompatible with (Mg + Ba02 + Zn), Al, and Mg alloys. When heated to decomposition it emits toxic fumes of NOx. See also BARIUM COMPOUNDS (soluble) and NITRATES. 

The A/59 is a plastic molded button-shaped electric igniter used for the ignition of the propellant powder expulsion charge in the Ml 12 and M123 photoflash cartridges. The pyrotechnic mixture—Formula 13—will tolerate a no-fire current of 1.3 A for 60 sec and will fire with 1.9 A in 50 msec. 

This mixture, Photofiash Powder, Type I, Class A, was used at the start of W. W. II for M46 Photoflash Bombshutis now relegated to small items such as the MI 15 Projectile Ground-Burst Simulator r which the flash and sound follow a pyrotechnic whistle. 

These mixtures are suitable for use in photoflash cartridge fuzes for I and 2-sec delay time. The large change in BT with slight changes... 

Photoflash cartridge, bomb)—Photoflash powder is a loose pyrote-technic mixture that yields a very large amount of light for a small fraction of a second on exploding. 

Photoflash, illuminating Solid rocket fuel Colored flame mixtures Smoke mixtures... 

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