Quickmatch

Aspects of special effects described in this chapter include fuses (quickmatch and plastic fuse), lances (small coloured flares), set-pieces and devices (assemblies consisting of various types of fireworks linked together), flash, bang and whistle compositions and daylight fireworks (smoke puffs and coloured smokes). Finally, the electrical firing of firework displays is discussed. 

The speed of burning of quickmatch is related to the chemical composition and the mass of the composition on the string. The linear burning rate equation enables a crude estimate of the speed of burning to be made. For example, a typical relationship already seen for gunpowder is given by equation (10.1), 

The primary safety considerations in the formulation, manufacture, and use of explosives are that they must never explode prematurely but always explode when desired. Often this balance is achieved with an insensitive main charge being initiated by the least amount of a more sensitive explosive. This concept is expanded to that of an explosive train in which a series of decreas-ingly sensitive explosives is ultimately sufficient to initiate an insensitive main charge. The sensitivity of explosives to initiation provides a common means of classification  

Other explosives may be added to explosive trains to sensitize certain components or add a time delay. There are as many combinations as necessary to 

Mercury fulminate detonators were widely replaced due to their extreme sensitivity. Contemporary simple nonelectric detonators contain a small quantity of primary explosive (often lead azide) which, once ignited by a fuse, ignites the more powerful base charge of a secondary explosive (an additional low explosive may be used between the fuse and the primary explosive). 

Often another controlled volume of low explosive is placed between the matchhead and the primary charge. This bums for a specified period introducing a delay (from a few milliseconds to a few seconds) into the detonator. However, any low explosive delay device syn. delay electric igniter) introduces imprecision because the chemicals are affected by moisture, temperature, and time. High precision delay electric detonators implant the match-head directly into the primary explosive and control the delay with an integrated circuit within the detonator. 

Detonators for ammunition include primary explosives to detonate the main charge. They may or may not be co inected to a fuze. 

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Group 3 Nitrate/metal compositions without sulphur Compositions with <35-65% chlorate Compositions with black powder Lead oxide/silicon with >60% lead oxides Perchlorate/metal Burn fast Large firework shells Fuse protected signal flares Pressed report cartridges in primary packagings Quickmatches in transport packagings Waterfalls Silver wheels Volcanoes Black powder delays Burn very violently with single-item explosions... 

Whilst it is apparent that the gunpowder substitute has been developed for use in munitions, it remains to be seen whether the material can be used to the same extent in hreworks. Obvious applications would be as replacements for quickmatch and piped match, both of which are notoriously prone to dampness during wet or humid conditions. 

The gunpowder explodes in a further fraction of a second, the explosion blowing the shell out of the mortar tube in the manner of a shot from a cannon. At the same time a return section of piped match is lit by the explosion, transferring flame back to the top compartment where it reaches the quickmatch placed across the head of the 25 mm pressed delay fuse. 

Whilst quickmatch can be used to form simple fuses for fireworks, both internally and externally, a burning time of some 40 sm is too long in instances when a more or less instantaneous ignition is required. Also, quickmatch is rather fragile and tends to kink or lose powder unless it is coated in some way. 

Figure 10.1 Wirebridge fusehead (bottom), quickmatch (middle) and piped match (top).

Figure 10.2 Diagram showing the variation of the burning rate of quickmatch with fuse-to-wall distance.

Plastic Igniter Cord (PIC) is a modern version of quickmatch in which the gunpowder is replaced by a delay composition, consisting essentially of lead dioxide and silicon, while the support material is aluminium or iron wire. A plastic tube encloses the fuse, as in the manner of electrical... 

Plastic fuse is routinely used as a fuse extension to quickmatch or piped match, especially when firing rockets, mines or shells. In the latter case, the piped match fuses from a crate of, say, ten shells connected via a single length of plastic fuse which will burn progressively to ignite each of the ten shells in turn. 

On the other hand, if a salvo of rockets is required, a fast-burning PIC can be uncoiled into the bottom of a flight-box (which is a box with a wire mesh floor containing rockets, whereby the sticks or tails protrude downwards). On ignition, the plastic fuse rapidly ignites each of the quickmatch fuses protruding from the nozzles of the rockets. 

AFTERGLOW The glowing remains produced by the firing of gunpowder-based products such as quickmatch. It is very important that any afterglow is extinguished, especially when reloading shells or mines into mortar tubes. 

MEAL POWDER A vcry fine particle-size gunpowder that is used for priming and making quickmatch. 

PIPED MATCH A fuse Consisting of quickmatch enclosed in a paper pipe that serves to increase the burning speed. 

QuicKMATCH A fuse cousistiug of gunpowder coated onto cotton yarn using an adhesive such as gum arabic. 

Quickmatch. Fast burning fuse made by impregnating cotton wick with mealed (finely powdered) or unmealed BkPdr. Gum arabic or dextrin is used as a binder. Quickmatch is highly sensitive to moisture and must be kept dry for proper functioning. It burns almost instantaneously when confined (Ref 23, pp 2-21 to 2-22 USSpec JAN-Q-378)... 

Quickmatch, which is-used as an initiator to transmit flame to pyrotechnic chges, con-... 

Quickmatch becomes a nearly instantaneous transfer line if enclosed in a narrow paper tube and is thus used under the name of Piped Match in fireworks for simultaneous initiation of several items (Ref 57, p 191)... 

Other devices for igniting fuse trains of pyrotechnic items are listed in Ref 44a, p 146, and described in Ref 50, pp 99-101 Ref 57, pp 191-92 207-08. Some of the devices, besides the previously mentioned "safety fuse" and "quickmatch", include delay elements. 

The rule should be to keep the more hazardous mixts at minimum size. Transfer lines (such as fuses, quickmatch, etc) between prime ignition and first fire are regarded as a part of the secondary ignition system... 

Description of Safety Fuse, Ignitacord, Quickmatch and PyrofuZe is given elsewhere in the text... 

Type 98 No 7 Mk 6 Model 1 Bomb contd four Thermite-filled electron fire pots. A central channel filled with quick match ran thru the length of the bomb. A BkPdr chge was located in the circular recess of the nose piece (pp 71—72) Type 98 No 7 Mk Model 2 Bomb contd a central Thermite core surrounded by a solidified kerosene, petrol, alcohol, soap mixture. A BkPdr burster chge was located in the nose. A copper tube contg quickmatch was located inside Thermite tube (pp 73—4) ... 

J- QUICKMATCH K- ILLUMINANT CHARGE L- FIRST-FIRE CHARGE... 

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