Matches repeatedly ignitible

Then the polyethylene is removed, the rods cut to desired lengths and coated with a combustible material, such as regenerated cellulose. The matches can be ignited by striking a rough surface such as sa nd paper] Note Dr. Ellern (Ref 57, p 72) states that the first repeatedly ignitable match wa s invented in 1934 in Hungary by Z. Foldi ... 

The physical integrity of a pyrotechnic formulation may, exceptionally, be threatened by evaporation. This can occur when a rather volatile compound is a necessary component because of unique properties that make it difficult or impossible to replace it with a more stable ingredient. Two such compounds have been described earlier One is metaldehyde of a sublimation point of about 112 C and found only in novelty items such as repeatedly ignitible matches, hence of little concern in commercial practice the other is the HC smoke ingredient hexachloroethane. Its vapor pressure, as eviden d by the odor at room temperature, is sufficient to cause concern. In practice, however, with tightly compressed and sealed mixtures in substantial units, the volatility of HC seems to cause no trouble. 

The test piece is ignited at one end with a match-fuse and the burning time is noted by a precision stop-watch from the instant of ignition to the final point. IBR is found by dividing time in seconds by 20. This exercise is repeated with a second piece and the average of the two is reported as the IBR of the pyrotechnic formulation. 

Mixtures of metal powders and nitrates are deceptively inert when tested in small quantities for properties of initiability. Sometimes it is quite difflcuit to ignite them with an ordinary match in an ash tray experiment. As has been mentioned repeatedly, such misleading demonstrable lack of activity is no guarantee for safe behavior under different circumstances. 

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