I’ve gotten a ton of practice with creating Rocket Candy fuses using KNO3. I figured I’d share my recipe.
Brandon’s Rocket Candy Fuse Recipe
- Determine length of 3 mm twine needed.
- Cut twine to exact length.
- Use Rocket Candy Calculator to determine $\text{KNO}_3$ and sugar amounts.
- Enter length of 3 mm twine.
- Enter density: 7 g/ft is HOT, 5 g/ft is not nearly as fast, and 3 g/ft is slow.
- Put cup of water in microwave for 2 minutes (optional—saves time).
- Add $\text{KNO}_3$.
- Add sugar.
- Add hot/warm water:
- You only need enough to fully dissolve the $\text{KNO}_3$ and sugar. All water is boiled/baked off.
- Adding too much water adds substantial time to the boil.
- Boil:
- Outside is recommended.
- Apply medium/high heat.
- Ensure all fuses get soaked.
- Stir regularly: once every 2 minutes in the beginning, and once every 30 seconds as it thickens. Flip twine occasionally.
- When water turns to “goo,” remove from heat and continue to stir for 20 seconds.
- Do not burn the fuses. The goo should be white, not brown.
- Remove from heat.
- Let cool 5–10 minutes:
- There is no huge rush, but they may get stiff and be hard to work with if you wait too long.
- Tighten fuses on grill or jig (optional—keeps them straight).
- Bake at 190°F for 20 minutes.
- Bake at 160°F for 4 hours:
- Do not burn fuses.
- They will be slightly limp, but will stiffen up quickly when brought to room temperature.
- Ideally, place in oven at 150°F an hour or more before they will be used.
- If baking is not an option, keep in a jar with silica or use another method to seal them:
- Vacuum sealers are good.
- Ziploc bags are fine, but it’s easy for them to leak.