Bismuth dragon eggs ignition issue

[chris v]

I've been having a problem with ignition of my stars. For every article I have read and video I have seen says that they will ignite with BP. I have tried some green mix I had to my mill powder I have with no success. Any suggestions

[SharkWhisperer]

I've been having a problem with ignition of my stars. For every article I have read and video I have seen says that they will ignite with BP. I have tried some green mix I had to my mill powder I have with no success. Any suggestions

I prime my bismuth DEs with one or two layers of a mixture containing 60% of slowish BP (65/25/10 made with hardwood airfloat charcoal; milled & wet granulated/riced fines <40 mesh), heated up with metal --15% powdered silicon metal to form a nice hot slag, 5% spherical Al for some extra heat (I use 5-uM atomized but you can probably use bright mesh -325, or 30 micron atomized), and an extra 20% KNO3 to oxidize the metals. Added 5% red gum on top and screen mixed 3x through a 20-mesh screen. Applied using 91% isopropyl alcohol spray while rolling in a round pie tin. Never failed me yet. I see no reason why a dextrin or SGRS binder with water couldn't be used instead of red gum, so long as you have incorporated enough nitrocellulose into your eggs (I aim for 5% final volume) to render them largely waterproof.

Gotta get a moderate rate, high-heat regular burn going. Some people add diatomaceous earth to make the surface more granular to catch fire easier, but I haven't needed it. If I were to go that route, I'd just mix in an extra 5% of 20-40 mesh BP grains after the other ingredients were sifted together and hand mix--if I'm adding granular protrusions, I want them to burn. These DEs are approximately 1.5-2 mm diameter before priming. After priming, they're about double that size (if you use two layers of prime--one is probably sufficient). Work great in mine bags and embedded in gerb matrix formulas; haven't tried them in shells.

My DE mix is 35% BiO3, 40% CuO, 20% MgAl -60 mesh, and 5% Al -325 (approx 40 uM spherical), bound with sufficient 10% NC in acetone to give a final NC concentration of approx 5% (you definitely don't want to go much lower than 4%). This requires adding quite a bit of NC lacquer and patience while stirring until the acetone evaporates sufficiently to give a workable hard putty for blade or screen cutting. If you try to work the putty too soon when it's too wet, the sticky NC will give you some headaches... These babies are loud!