Dec 17, 2021 · Step 2: Rust the metal. Now it's time to mix your solution. Make sure you wear your goggles and gloves and mix 480 ml of hydrogen peroxide, 60 ml of white vinegar and 1/2 tbsp salt. Mix it all in a cup or the same spray bottle and make sure everything dissolves well before using. Now spray some solution onto your fire pit so that it covers