Thanks-
FYI, we have used technical grade (85%) Si in hot igniters, Potassium nitrate was sufficient oxidizer with a few % of fine black powder included when
bound with nitrocellulose lacquer and ignited by some medium sized black powder grains pressed into the surface before drying.
A thermite of Lead tetroxide and the same amorphous Silicon was briefly tested, this worked fine with a black powder first fire also- but was too
sensitive to impact (and toxic) for our comfort. If you need a shock to flame transducer element for use with shock tube or similar, you might try a
pellet of this "red thermite".
Much the same effect as the Si/KNO3 prime was achieved from a water bound prime mixture of Potassium perchlorate, red gum, diatomaceous
earth and a bit of fine Aluminum, Vanadium pentoxide, a few % each of charcoal and wood flour to produce a rough, fuzzy surface, with gum Arabic for
binding and guar or xanthan gum to control consistency while wet. I would have to dig for the exact %.
That prime may be used with any star mixture that can stand a water bound prime, without producing any sensitive or hygroscopic double replacement
products with other oxidizers. Chlorate, nitrate, Potassium or ammonium perchlorate, all good as long as there is no uncoated magnesium or high Mg %
magnalium present to react with oxidizers when damped.
The water bound mixture with diatomaceous earth was cheaper and did not involve solvent fumes, so we went with that-
All these compositions function by producing drops of a sticky, molten glassy slag stuck to the surface of a star. These hot slag droplets stay where
they are needed, protecting hot spots under them until a fast moving star slows down enough not to be blown out.
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