Text specifies Hemp or Pawlownia coal as the charcoal type. In place of dextrin, original formula calls for 2% glutinous rice starch. While unsuitable for shells under 3 inches, is much safer than H3 burst. Burn rate increases with pressure, so making shell walls thicker will improve the break. If the shell wall is too weak, however, the break will be very poor, as the pressure required for the proper burn rate will never be reached.