Rocket candy Components Extra chemicals
People use many different extra chemicals. These are just the ones that are used the most. Metal oxides are one group of extra chemicals. These make the rocket candy burn faster. Metal oxides work best at levels from 1 to 5 percent. This means between one and five grams of extra chemical for every one hundred grams in the fuel. The most common metal oxide is called iron oxide. The most common type of iron oxide is red iron oxide.