WARNING: THIS COMPOSITION, WHEN MIXED, IS EXCEEDINGLY DANGEROUS. IT IS VERY SENSITIVE TO SHOCK, FRICTION, AND ALL OTHER PHYSICAL OR ELECTRICAL DISTURBANCES
Armstrongs mixture is an extremely friction and shock sensitive mixture, that consists of a powerful oxidizer, such as potassium chlorate or potassium perchlorate along with red phosphorus. In consumer fireworks, potassium chlorate is used, since it is much more friction sensitive than potassium perchlorate.
When mixed, the composition becomes very sensitive. To avoid the risk of ignition, the red phosphorus is wetted with demineralised water before mixing, and after mixing, the mixture is dried. Never mix more than 1 gram of mixture! In consumer fireworks, only 10 mg is used.
Amateur pyrotechnicians should avoid this mixture - especially the chlorate-based - since the mixture is too sensitive to handle or store for the normal hobby pyrotechnician.
The chlorate version can be detonated with almost any kind of friction, such as a small blow with a hammer. The perchlorate version is more stable, and will ignite with the spark from a fuse, however should still be handled with care.
This list of contents is from a pack of strip caps made by Edison Giocattoli, in Italy. These caps contain less than 0.20 grains per cap, as required by US law. The pyrotechnic contents a follows:
When dry, this composition can detonate with so much as a breeze or the lightest amount of pressure or friction.
HANDLE WITH EXTREME CAUTION!