A few safety notes — don’t hammer these comps — they are a form a flash powder. Wear cotton clothing and appropriate safety gear when mixing and pressing these.
The Vaseline should be dissolved in VM&P Naptha. While I don’t know if these compositions will work for bottle rockets, I have developed a couple of magnalium-based compositions over the past year that work well for rockets in the one pound to four pound range. The benefit of magnalium-based compositions is that they can be mixed, pressed, and flown in a matter of minutes. There is no potassium dichromate to mess with, and no drying time of extended prep time required for the composition. This makes these rockets ideal for for people to be able to build and fly at club events legally. The first formula, red magnalium chuffer rockets, was published in the December 2004 PGI journal by Doc Steinberg and I. I have since gone on to develop formulas for green and yellow as well. I flew four pound versions of the red, green, and yellow compositions at the recent FPAG 4F event in November. Note that all of these compositions are pressed on standard blackpowder rocket tooling with chokes that are as tall as the inside diameter of the tube is wide. I have since discovered that the VM&P Naphtha is responsible for the chuffing effect, and allowing the Naphtha to evaporate completely from the mix results in no chuff whatsoever. With good strong paper tubes, you could probably omit the Vaseline all together. I have been using 2600 pounds of force to press these rockets. If you have a copy of the PGI article John and I published in December 2004, I provide a calculation for converting pressure to force based on the size of the ram in your press. You can use more force, but the additional compaction slows the burn rate somewhat. -Dave Stoddard