To use powdered gelatin, combine 1 part unflavored powdered gelatin with 2 parts cold water. (1/4 cup gelatin and 1/2 cup water will yield about 8 balloons.) Whisk the gelatin and water together, then let it sit and soften the gelatin. Once the gelatin has absorbed the water, gently heat it up in the microwave in short intervals. Try to swirl the gelatin rather than stirring it, since stirring can lead to a lot of air bubbles. Once it's entirely melted, let it cool to barely warm before dipping the balloons as described above. Reheat the gelatin as necessary to get a dippable consistency.