Lancaster Silver, 8mm pumped starsSilver stars are beautiful pyrotechnic effects in which various forms of aluminum are employed to obtain diverse appearances of silver flame, fire dust etc. Due to the high metal content the compositions may be somewhat harder to consolidate and a hot (non-BP) prime may be necessary to properly light the stars.
Flitter is probably the best choice, but "Bright" or "Bronze" grades may also be employed. Various burn durations and flame sizes are obtained when varying the ratios oxidizer-fuel from A to D. For round stars the starch content may be raised to 8-10% for easy consolidation. The stars need hot two-stage primes employing e.g. thermite or silicon.
The cut stars are used as cores for star rolling and give an intense light when the star burns out. The cores burn very fast and move around violently when unevenly ignited (they "swim"), producing an unsightly final stage of the flower. To avoid this the cores are coated with a "core coating comp" before rolling proceeds. Boric acid in solid form can be avoided when we dissolve 2% of it in the solvent.